mfd: TWL4030 core driver

This patch adds the core of the TWL4030 driver, which supports
chips including the TPS65950.  These chips are multi-function; see

  http://focus.ti.com/docs/prod/folders/print/tps65950.html

Public specs are in the works.  For now, the block diagram on
the second page of the datasheet is fairly informative.

There are some known issues with this core code.  Most notably,
the IRQ dispatching needs simplification (to use more of genirq),
generalization (integrating support for secondary IRQ dispatch
as well as primary, and removing the build dependency on OMAP),
and then probably updating to leverage threaded IRQ support
(expected to arrive in mainline "soon").

Once the core is in mainline, drivers for other parts of this
chip can follow its lead and start swimming upstream too.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>

1 files changed, 1257 insertions, 0 deletions

diff --git a/drivers/mfd/twl4030-core.c b/drivers/mfd/twl4030-core.c
new file mode 100644
index 000000000000..4af1624987c5
--- /dev/null
+++ b/drivers/mfd/twl4030-core.c
@@ -0,0 +1,1257 @@
+/*
+ * twl4030_core.c - driver for TWL4030/TPS659x0 PM and audio CODEC devices
+ *
+ * Copyright (C) 2005-2006 Texas Instruments, Inc.
+ *
+ * Modifications to defer interrupt handling to a kernel thread:
+ * Copyright (C) 2006 MontaVista Software, Inc.
+ *
+ * Based on tlv320aic23.c:
+ * Copyright (c) by Kai Svahn <kai.svahn@nokia.com>
+ *
+ * Code cleanup and modifications to IRQ handler.
+ * by syed khasim <x0khasim@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/random.h>
+#include <linux/kthread.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+
+#include <linux/i2c.h>
+#include <linux/i2c/twl4030.h>
+
+
+/*
+ * The TWL4030 "Triton 2" is one of a family of a multi-function "Power
+ * Management and System Companion Device" chips originally designed for
+ * use in OMAP2 and OMAP 3 based systems.  Its control interfaces use I2C,
+ * often at around 3 Mbit/sec, including for interrupt handling.
+ *
+ * This driver core provides genirq support for the interrupts emitted,
+ * by the various modules, and exports register access primitives.
+ *
+ * FIXME this driver currently requires use of the first interrupt line
+ * (and associated registers).
+ */
+
+#define DRIVER_NAME			"twl4030"
+
+#if defined(CONFIG_TWL4030_BCI_BATTERY) || \
+	defined(CONFIG_TWL4030_BCI_BATTERY_MODULE)
+#define twl_has_bci()		true
+#else
+#define twl_has_bci()		false
+#endif
+
+#if defined(CONFIG_KEYBOARD_TWL4030) || defined(CONFIG_KEYBOARD_TWL4030_MODULE)
+#define twl_has_keypad()	true
+#else
+#define twl_has_keypad()	false
+#endif
+
+#if defined(CONFIG_GPIO_TWL4030) || defined(CONFIG_GPIO_TWL4030_MODULE)
+#define twl_has_gpio()	true
+#else
+#define twl_has_gpio()	false
+#endif
+
+#if defined(CONFIG_TWL4030_MADC) || defined(CONFIG_TWL4030_MADC_MODULE)
+#define twl_has_madc()	true
+#else
+#define twl_has_madc()	false
+#endif
+
+#if defined(CONFIG_RTC_DRV_TWL4030) || defined(CONFIG_RTC_DRV_TWL4030_MODULE)
+#define twl_has_rtc()	true
+#else
+#define twl_has_rtc()	false
+#endif
+
+#if defined(CONFIG_TWL4030_USB) || defined(CONFIG_TWL4030_USB_MODULE)
+#define twl_has_usb()	true
+#else
+#define twl_has_usb()	false
+#endif
+
+static inline void activate_irq(int irq)
+{
+#ifdef CONFIG_ARM
+	/* ARM requires an extra step to clear IRQ_NOREQUEST, which it
+	 * sets on behalf of every irq_chip.  Also sets IRQ_NOPROBE.
+	 */
+	set_irq_flags(irq, IRQF_VALID);
+#else
+	/* same effect on other architectures */
+	set_irq_noprobe(irq);
+#endif
+}
+
+/* Primary Interrupt Handler on TWL4030 Registers */
+
+/* Register Definitions */
+
+#define REG_PIH_ISR_P1			(0x1)
+#define REG_PIH_ISR_P2			(0x2)
+#define REG_PIH_SIR			(0x3)
+
+/* Triton Core internal information (BEGIN) */
+
+/* Last - for index max*/
+#define TWL4030_MODULE_LAST		TWL4030_MODULE_SECURED_REG
+
+#define TWL4030_NUM_SLAVES		4
+
+
+/* Base Address defns for twl4030_map[] */
+
+/* subchip/slave 0 - USB ID */
+#define TWL4030_BASEADD_USB		0x0000
+
+/* subchip/slave 1 - AUD ID */
+#define TWL4030_BASEADD_AUDIO_VOICE	0x0000
+#define TWL4030_BASEADD_GPIO		0x0098
+#define TWL4030_BASEADD_INTBR		0x0085
+#define TWL4030_BASEADD_PIH		0x0080
+#define TWL4030_BASEADD_TEST		0x004C
+
+/* subchip/slave 2 - AUX ID */
+#define TWL4030_BASEADD_INTERRUPTS	0x00B9
+#define TWL4030_BASEADD_LED		0x00EE
+#define TWL4030_BASEADD_MADC		0x0000
+#define TWL4030_BASEADD_MAIN_CHARGE	0x0074
+#define TWL4030_BASEADD_PRECHARGE	0x00AA
+#define TWL4030_BASEADD_PWM0		0x00F8
+#define TWL4030_BASEADD_PWM1		0x00FB
+#define TWL4030_BASEADD_PWMA		0x00EF
+#define TWL4030_BASEADD_PWMB		0x00F1
+#define TWL4030_BASEADD_KEYPAD		0x00D2
+
+/* subchip/slave 3 - POWER ID */
+#define TWL4030_BASEADD_BACKUP		0x0014
+#define TWL4030_BASEADD_INT		0x002E
+#define TWL4030_BASEADD_PM_MASTER	0x0036
+#define TWL4030_BASEADD_PM_RECEIVER	0x005B
+#define TWL4030_BASEADD_RTC		0x001C
+#define TWL4030_BASEADD_SECURED_REG	0x0000
+
+/* Triton Core internal information (END) */
+
+
+/* Few power values */
+#define R_CFG_BOOT			0x05
+#define R_PROTECT_KEY			0x0E
+
+/* access control values for R_PROTECT_KEY */
+#define KEY_UNLOCK1			0xce
+#define KEY_UNLOCK2			0xec
+#define KEY_LOCK			0x00
+
+/* some fields in R_CFG_BOOT */
+#define HFCLK_FREQ_19p2_MHZ		(1 << 0)
+#define HFCLK_FREQ_26_MHZ		(2 << 0)
+#define HFCLK_FREQ_38p4_MHZ		(3 << 0)
+#define HIGH_PERF_SQ			(1 << 3)
+
+
+/*----------------------------------------------------------------------*/
+
+/**
+ * struct twl4030_mod_iregs - TWL module IMR/ISR regs to mask/clear at init
+ * @mod_no: TWL4030 module number (e.g., TWL4030_MODULE_GPIO)
+ * @sih_ctrl: address of module SIH_CTRL register
+ * @reg_cnt: number of IMR/ISR regs
+ * @imrs: pointer to array of TWL module interrupt mask register indices
+ * @isrs: pointer to array of TWL module interrupt status register indices
+ *
+ * Ties together TWL4030 modules and lists of IMR/ISR registers to mask/clear
+ * during twl_init_irq().
+ */
+struct twl4030_mod_iregs {
+	const u8 mod_no;
+	const u8 sih_ctrl;
+	const u8 reg_cnt;
+	const u8 *imrs;
+	const u8 *isrs;
+};
+
+/* TWL4030 INT module interrupt mask registers */
+static const u8 __initconst twl4030_int_imr_regs[] = {
+	TWL4030_INT_PWR_IMR1,
+	TWL4030_INT_PWR_IMR2,
+};
+
+/* TWL4030 INT module interrupt status registers */
+static const u8 __initconst twl4030_int_isr_regs[] = {
+	TWL4030_INT_PWR_ISR1,
+	TWL4030_INT_PWR_ISR2,
+};
+
+/* TWL4030 INTERRUPTS module interrupt mask registers */
+static const u8 __initconst twl4030_interrupts_imr_regs[] = {
+	TWL4030_INTERRUPTS_BCIIMR1A,
+	TWL4030_INTERRUPTS_BCIIMR1B,
+	TWL4030_INTERRUPTS_BCIIMR2A,
+	TWL4030_INTERRUPTS_BCIIMR2B,
+};
+
+/* TWL4030 INTERRUPTS module interrupt status registers */
+static const u8 __initconst twl4030_interrupts_isr_regs[] = {
+	TWL4030_INTERRUPTS_BCIISR1A,
+	TWL4030_INTERRUPTS_BCIISR1B,
+	TWL4030_INTERRUPTS_BCIISR2A,
+	TWL4030_INTERRUPTS_BCIISR2B,
+};
+
+/* TWL4030 MADC module interrupt mask registers */
+static const u8 __initconst twl4030_madc_imr_regs[] = {
+	TWL4030_MADC_IMR1,
+	TWL4030_MADC_IMR2,
+};
+
+/* TWL4030 MADC module interrupt status registers */
+static const u8 __initconst twl4030_madc_isr_regs[] = {
+	TWL4030_MADC_ISR1,
+	TWL4030_MADC_ISR2,
+};
+
+/* TWL4030 keypad module interrupt mask registers */
+static const u8 __initconst twl4030_keypad_imr_regs[] = {
+	TWL4030_KEYPAD_KEYP_IMR1,
+	TWL4030_KEYPAD_KEYP_IMR2,
+};
+
+/* TWL4030 keypad module interrupt status registers */
+static const u8 __initconst twl4030_keypad_isr_regs[] = {
+	TWL4030_KEYPAD_KEYP_ISR1,
+	TWL4030_KEYPAD_KEYP_ISR2,
+};
+
+/* TWL4030 GPIO module interrupt mask registers */
+static const u8 __initconst twl4030_gpio_imr_regs[] = {
+	REG_GPIO_IMR1A,
+	REG_GPIO_IMR1B,
+	REG_GPIO_IMR2A,
+	REG_GPIO_IMR2B,
+	REG_GPIO_IMR3A,
+	REG_GPIO_IMR3B,
+};
+
+/* TWL4030 GPIO module interrupt status registers */
+static const u8 __initconst twl4030_gpio_isr_regs[] = {
+	REG_GPIO_ISR1A,
+	REG_GPIO_ISR1B,
+	REG_GPIO_ISR2A,
+	REG_GPIO_ISR2B,
+	REG_GPIO_ISR3A,
+	REG_GPIO_ISR3B,
+};
+
+/* TWL4030 modules that have IMR/ISR registers that must be masked/cleared */
+static const struct twl4030_mod_iregs __initconst twl4030_mod_regs[] = {
+	{
+		.mod_no	  = TWL4030_MODULE_INT,
+		.sih_ctrl = TWL4030_INT_PWR_SIH_CTRL,
+		.reg_cnt  = ARRAY_SIZE(twl4030_int_imr_regs),
+		.imrs	  = twl4030_int_imr_regs,
+		.isrs	  = twl4030_int_isr_regs,
+	},
+	{
+		.mod_no	  = TWL4030_MODULE_INTERRUPTS,
+		.sih_ctrl = TWL4030_INTERRUPTS_BCISIHCTRL,
+		.reg_cnt  = ARRAY_SIZE(twl4030_interrupts_imr_regs),
+		.imrs	  = twl4030_interrupts_imr_regs,
+		.isrs	  = twl4030_interrupts_isr_regs,
+	},
+	{
+		.mod_no	  = TWL4030_MODULE_MADC,
+		.sih_ctrl = TWL4030_MADC_SIH_CTRL,
+		.reg_cnt  = ARRAY_SIZE(twl4030_madc_imr_regs),
+		.imrs	  = twl4030_madc_imr_regs,
+		.isrs	  = twl4030_madc_isr_regs,
+	},
+	{
+		.mod_no	  = TWL4030_MODULE_KEYPAD,
+		.sih_ctrl = TWL4030_KEYPAD_KEYP_SIH_CTRL,
+		.reg_cnt  = ARRAY_SIZE(twl4030_keypad_imr_regs),
+		.imrs	  = twl4030_keypad_imr_regs,
+		.isrs	  = twl4030_keypad_isr_regs,
+	},
+	{
+		.mod_no	  = TWL4030_MODULE_GPIO,
+		.sih_ctrl = REG_GPIO_SIH_CTRL,
+		.reg_cnt  = ARRAY_SIZE(twl4030_gpio_imr_regs),
+		.imrs	  = twl4030_gpio_imr_regs,
+		.isrs	  = twl4030_gpio_isr_regs,
+	},
+};
+
+/*----------------------------------------------------------------*/
+
+/* is driver active, bound to a chip? */
+static bool inuse;
+
+/* Structure for each TWL4030 Slave */
+struct twl4030_client {
+	struct i2c_client *client;
+	u8 address;
+
+	/* max numb of i2c_msg required is for read =2 */
+	struct i2c_msg xfer_msg[2];
+
+	/* To lock access to xfer_msg */
+	struct mutex xfer_lock;
+};
+
+static struct twl4030_client twl4030_modules[TWL4030_NUM_SLAVES];
+
+
+/* mapping the module id to slave id and base address */
+struct twl4030mapping {
+	unsigned char sid;	/* Slave ID */
+	unsigned char base;	/* base address */
+};
+
+static struct twl4030mapping twl4030_map[TWL4030_MODULE_LAST + 1] = {
+	/*
+	 * NOTE:  don't change this table without updating the
+	 * <linux/i2c/twl4030.h> defines for TWL4030_MODULE_*
+	 * so they continue to match the order in this table.
+	 */
+
+	{ 0, TWL4030_BASEADD_USB },
+
+	{ 1, TWL4030_BASEADD_AUDIO_VOICE },
+	{ 1, TWL4030_BASEADD_GPIO },
+	{ 1, TWL4030_BASEADD_INTBR },
+	{ 1, TWL4030_BASEADD_PIH },
+	{ 1, TWL4030_BASEADD_TEST },
+
+	{ 2, TWL4030_BASEADD_KEYPAD },
+	{ 2, TWL4030_BASEADD_MADC },
+	{ 2, TWL4030_BASEADD_INTERRUPTS },
+	{ 2, TWL4030_BASEADD_LED },
+	{ 2, TWL4030_BASEADD_MAIN_CHARGE },
+	{ 2, TWL4030_BASEADD_PRECHARGE },
+	{ 2, TWL4030_BASEADD_PWM0 },
+	{ 2, TWL4030_BASEADD_PWM1 },
+	{ 2, TWL4030_BASEADD_PWMA },
+	{ 2, TWL4030_BASEADD_PWMB },
+
+	{ 3, TWL4030_BASEADD_BACKUP },
+	{ 3, TWL4030_BASEADD_INT },
+	{ 3, TWL4030_BASEADD_PM_MASTER },
+	{ 3, TWL4030_BASEADD_PM_RECEIVER },
+	{ 3, TWL4030_BASEADD_RTC },
+	{ 3, TWL4030_BASEADD_SECURED_REG },
+};
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * TWL4030 doesn't have PIH mask, hence dummy function for mask
+ * and unmask of the (eight) interrupts reported at that level ...
+ * masking is only available from SIH (secondary) modules.
+ */
+
+static void twl4030_i2c_ackirq(unsigned int irq)
+{
+}
+
+static void twl4030_i2c_disableint(unsigned int irq)
+{
+}
+
+static void twl4030_i2c_enableint(unsigned int irq)
+{
+}
+
+static struct irq_chip twl4030_irq_chip = {
+	.name	= "twl4030",
+	.ack	= twl4030_i2c_ackirq,
+	.mask	= twl4030_i2c_disableint,
+	.unmask	= twl4030_i2c_enableint,
+};
+
+/*----------------------------------------------------------------------*/
+
+/* Exported Functions */
+
+/**
+ * twl4030_i2c_write - Writes a n bit register in TWL4030
+ * @mod_no: module number
+ * @value: an array of num_bytes+1 containing data to write
+ * @reg: register address (just offset will do)
+ * @num_bytes: number of bytes to transfer
+ *
+ * IMPORTANT: for 'value' parameter: Allocate value num_bytes+1 and
+ * valid data starts at Offset 1.
+ *
+ * Returns the result of operation - 0 is success
+ */
+int twl4030_i2c_write(u8 mod_no, u8 *value, u8 reg, u8 num_bytes)
+{
+	int ret;
+	int sid;
+	struct twl4030_client *twl;
+	struct i2c_msg *msg;
+
+	if (unlikely(mod_no > TWL4030_MODULE_LAST)) {
+		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
+		return -EPERM;
+	}
+	sid = twl4030_map[mod_no].sid;
+	twl = &twl4030_modules[sid];
+
+	if (unlikely(!inuse)) {
+		pr_err("%s: client %d is not initialized\n", DRIVER_NAME, sid);
+		return -EPERM;
+	}
+	mutex_lock(&twl->xfer_lock);
+	/*
+	 * [MSG1]: fill the register address data
+	 * fill the data Tx buffer
+	 */
+	msg = &twl->xfer_msg[0];
+	msg->addr = twl->address;
+	msg->len = num_bytes + 1;
+	msg->flags = 0;
+	msg->buf = value;
+	/* over write the first byte of buffer with the register address */
+	*value = twl4030_map[mod_no].base + reg;
+	ret = i2c_transfer(twl->client->adapter, twl->xfer_msg, 1);
+	mutex_unlock(&twl->xfer_lock);
+
+	/* i2cTransfer returns num messages.translate it pls.. */
+	if (ret >= 0)
+		ret = 0;
+	return ret;
+}
+EXPORT_SYMBOL(twl4030_i2c_write);
+
+/**
+ * twl4030_i2c_read - Reads a n bit register in TWL4030
+ * @mod_no: module number
+ * @value: an array of num_bytes containing data to be read
+ * @reg: register address (just offset will do)
+ * @num_bytes: number of bytes to transfer
+ *
+ * Returns result of operation - num_bytes is success else failure.
+ */
+int twl4030_i2c_read(u8 mod_no, u8 *value, u8 reg, u8 num_bytes)
+{
+	int ret;
+	u8 val;
+	int sid;
+	struct twl4030_client *twl;
+	struct i2c_msg *msg;
+
+	if (unlikely(mod_no > TWL4030_MODULE_LAST)) {
+		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
+		return -EPERM;
+	}
+	sid = twl4030_map[mod_no].sid;
+	twl = &twl4030_modules[sid];
+
+	if (unlikely(!inuse)) {
+		pr_err("%s: client %d is not initialized\n", DRIVER_NAME, sid);
+		return -EPERM;
+	}
+	mutex_lock(&twl->xfer_lock);
+	/* [MSG1] fill the register address data */
+	msg = &twl->xfer_msg[0];
+	msg->addr = twl->address;
+	msg->len = 1;
+	msg->flags = 0;	/* Read the register value */
+	val = twl4030_map[mod_no].base + reg;
+	msg->buf = &val;
+	/* [MSG2] fill the data rx buffer */
+	msg = &twl->xfer_msg[1];
+	msg->addr = twl->address;
+	msg->flags = I2C_M_RD;	/* Read the register value */
+	msg->len = num_bytes;	/* only n bytes */
+	msg->buf = value;
+	ret = i2c_transfer(twl->client->adapter, twl->xfer_msg, 2);
+	mutex_unlock(&twl->xfer_lock);
+
+	/* i2cTransfer returns num messages.translate it pls.. */
+	if (ret >= 0)
+		ret = 0;
+	return ret;
+}
+EXPORT_SYMBOL(twl4030_i2c_read);
+
+/**
+ * twl4030_i2c_write_u8 - Writes a 8 bit register in TWL4030
+ * @mod_no: module number
+ * @value: the value to be written 8 bit
+ * @reg: register address (just offset will do)
+ *
+ * Returns result of operation - 0 is success
+ */
+int twl4030_i2c_write_u8(u8 mod_no, u8 value, u8 reg)
+{
+
+	/* 2 bytes offset 1 contains the data offset 0 is used by i2c_write */
+	u8 temp_buffer[2] = { 0 };
+	/* offset 1 contains the data */
+	temp_buffer[1] = value;
+	return twl4030_i2c_write(mod_no, temp_buffer, reg, 1);
+}
+EXPORT_SYMBOL(twl4030_i2c_write_u8);
+
+/**
+ * twl4030_i2c_read_u8 - Reads a 8 bit register from TWL4030
+ * @mod_no: module number
+ * @value: the value read 8 bit
+ * @reg: register address (just offset will do)
+ *
+ * Returns result of operation - 0 is success
+ */
+int twl4030_i2c_read_u8(u8 mod_no, u8 *value, u8 reg)
+{
+	return twl4030_i2c_read(mod_no, value, reg, 1);
+}
+EXPORT_SYMBOL(twl4030_i2c_read_u8);
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * do_twl4030_module_irq() is the desc->handle method for each of the twl4030
+ * module interrupts that doesn't chain to another irq_chip (GPIO, power, etc).
+ * It executes in kernel thread context.  On entry, cpu interrupts are disabled.
+ */
+static void do_twl4030_module_irq(unsigned int irq, irq_desc_t *desc)
+{
+	struct irqaction *action;
+	const unsigned int cpu = smp_processor_id();
+
+	/*
+	 * Earlier this was desc->triggered = 1;
+	 */
+	desc->status |= IRQ_LEVEL;
+
+	/*
+	 * The desc->handle method would normally call the desc->chip->ack
+	 * method here, but we won't bother since our ack method is NULL.
+	 */
+
+	if (!desc->depth) {
+		kstat_cpu(cpu).irqs[irq]++;
+
+		action = desc->action;
+		if (action) {
+			int ret;
+			int status = 0;
+			int retval = 0;
+
+			local_irq_enable();
+
+			do {
+				/* Call the ISR with cpu interrupts enabled */
+				ret = action->handler(irq, action->dev_id);
+				if (ret == IRQ_HANDLED)
+					status |= action->flags;
+				retval |= ret;
+				action = action->next;
+			} while (action);
+
+			if (status & IRQF_SAMPLE_RANDOM)
+				add_interrupt_randomness(irq);
+
+			local_irq_disable();
+
+			if (retval != IRQ_HANDLED)
+				printk(KERN_ERR "ISR for TWL4030 module"
+					" irq %d can't handle interrupt\n",
+					irq);
+
+			/*
+			 * Here is where we should call the unmask method, but
+			 * again we won't bother since it is NULL.
+			 */
+		} else
+			printk(KERN_CRIT "TWL4030 module irq %d has no ISR"
+					" but can't be masked!\n", irq);
+	} else
+		printk(KERN_CRIT "TWL4030 module irq %d is disabled but can't"
+				" be masked!\n", irq);
+}
+
+static unsigned twl4030_irq_base;
+
+static struct completion irq_event;
+
+/*
+ * This thread processes interrupts reported by the Primary Interrupt Handler.
+ */
+static int twl4030_irq_thread(void *data)
+{
+	long irq = (long)data;
+	irq_desc_t *desc = irq_desc + irq;
+	static unsigned i2c_errors;
+	const static unsigned max_i2c_errors = 100;
+
+	daemonize("twl4030-irq");
+	current->flags |= PF_NOFREEZE;
+
+	while (!kthread_should_stop()) {
+		int ret;
+		int module_irq;
+		u8 pih_isr;
+
+		/* Wait for IRQ, then read PIH irq status (also blocking) */
+		wait_for_completion_interruptible(&irq_event);
+
+		ret = twl4030_i2c_read_u8(TWL4030_MODULE_PIH, &pih_isr,
+					  REG_PIH_ISR_P1);
+		if (ret) {
+			pr_warning("%s: I2C error %d reading PIH ISR\n",
+					DRIVER_NAME, ret);
+			if (++i2c_errors >= max_i2c_errors) {
+				printk(KERN_ERR "Maximum I2C error count"
+						" exceeded.  Terminating %s.\n",
+						__func__);
+				break;
+			}
+			complete(&irq_event);
+			continue;
+		}
+
+		/* these handlers deal with the relevant SIH irq status */
+		local_irq_disable();
+		for (module_irq = twl4030_irq_base;
+				pih_isr;
+				pih_isr >>= 1, module_irq++) {
+			if (pih_isr & 0x1) {
+				irq_desc_t *d = irq_desc + module_irq;
+
+				d->handle_irq(module_irq, d);
+			}
+		}
+		local_irq_enable();
+
+		desc->chip->unmask(irq);
+	}
+
+	return 0;
+}
+
+/*
+ * do_twl4030_irq() is the desc->handle method for the twl4030 interrupt.
+ * This is a chained interrupt, so there is no desc->action method for it.
+ * Now we need to query the interrupt controller in the twl4030 to determine
+ * which module is generating the interrupt request.  However, we can't do i2c
+ * transactions in interrupt context, so we must defer that work to a kernel
+ * thread.  All we do here is acknowledge and mask the interrupt and wakeup
+ * the kernel thread.
+ */
+static void do_twl4030_irq(unsigned int irq, irq_desc_t *desc)
+{
+	const unsigned int cpu = smp_processor_id();
+
+	/*
+	 * Earlier this was desc->triggered = 1;
+	 */
+	desc->status |= IRQ_LEVEL;
+
+	/*
+	 * Acknowledge, clear _AND_ disable the interrupt.
+	 */
+	desc->chip->ack(irq);
+
+	if (!desc->depth) {
+		kstat_cpu(cpu).irqs[irq]++;
+
+		complete(&irq_event);
+	}
+}
+
+static struct task_struct * __init start_twl4030_irq_thread(long irq)
+{
+	struct task_struct *thread;
+
+	init_completion(&irq_event);
+	thread = kthread_run(twl4030_irq_thread, (void *)irq,
+			     "twl4030 irq %ld", irq);
+	if (!thread)
+		pr_err("%s: could not create twl4030 irq %ld thread!\n",
+		       DRIVER_NAME, irq);
+
+	return thread;
+}
+
+/*----------------------------------------------------------------------*/
+
+static int add_children(struct twl4030_platform_data *pdata)
+{
+	struct platform_device	*pdev = NULL;
+	struct twl4030_client	*twl = NULL;
+	int			status = 0;
+
+	if (twl_has_bci() && pdata->bci) {
+		twl = &twl4030_modules[3];
+
+		pdev = platform_device_alloc("twl4030_bci", -1);
+		if (!pdev) {
+			pr_debug("%s: can't alloc bci dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+			goto err;
+		}
+
+		if (status == 0) {
+			pdev->dev.parent = &twl->client->dev;
+			status = platform_device_add_data(pdev, pdata->bci,
+					sizeof(*pdata->bci));
+			if (status < 0) {
+				dev_dbg(&twl->client->dev,
+					"can't add bci data, %d\n",
+					status);
+				goto err;
+			}
+		}
+
+		if (status == 0) {
+			struct resource r = {
+				.start = TWL4030_PWRIRQ_CHG_PRES,
+				.flags = IORESOURCE_IRQ,
+			};
+
+			status = platform_device_add_resources(pdev, &r, 1);
+		}
+
+		if (status == 0)
+			status = platform_device_add(pdev);
+
+		if (status < 0) {
+			platform_device_put(pdev);
+			dev_dbg(&twl->client->dev,
+					"can't create bci dev, %d\n",
+					status);
+			goto err;
+		}
+	}
+
+	if (twl_has_gpio() && pdata->gpio) {
+		twl = &twl4030_modules[1];
+
+		pdev = platform_device_alloc("twl4030_gpio", -1);
+		if (!pdev) {
+			pr_debug("%s: can't alloc gpio dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+			goto err;
+		}
+
+		/* more driver model init */
+		if (status == 0) {
+			pdev->dev.parent = &twl->client->dev;
+			/* device_init_wakeup(&pdev->dev, 1); */
+
+			status = platform_device_add_data(pdev, pdata->gpio,
+					sizeof(*pdata->gpio));
+			if (status < 0) {
+				dev_dbg(&twl->client->dev,
+					"can't add gpio data, %d\n",
+					status);
+				goto err;
+			}
+		}
+
+		/* GPIO module IRQ */
+		if (status == 0) {
+			struct resource	r = {
+				.start = pdata->irq_base + 0,
+				.flags = IORESOURCE_IRQ,
+			};
+
+			status = platform_device_add_resources(pdev, &r, 1);
+		}
+
+		if (status == 0)
+			status = platform_device_add(pdev);
+
+		if (status < 0) {
+			platform_device_put(pdev);
+			dev_dbg(&twl->client->dev,
+					"can't create gpio dev, %d\n",
+					status);
+			goto err;
+		}
+	}
+
+	if (twl_has_keypad() && pdata->keypad) {
+		pdev = platform_device_alloc("twl4030_keypad", -1);
+		if (pdev) {
+			twl = &twl4030_modules[2];
+			pdev->dev.parent = &twl->client->dev;
+			device_init_wakeup(&pdev->dev, 1);
+			status = platform_device_add_data(pdev, pdata->keypad,
+					sizeof(*pdata->keypad));
+			if (status < 0) {
+				dev_dbg(&twl->client->dev,
+					"can't add keypad data, %d\n",
+					status);
+				platform_device_put(pdev);
+				goto err;
+			}
+			status = platform_device_add(pdev);
+			if (status < 0) {
+				platform_device_put(pdev);
+				dev_dbg(&twl->client->dev,
+						"can't create keypad dev, %d\n",
+						status);
+				goto err;
+			}
+		} else {
+			pr_debug("%s: can't alloc keypad dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+			goto err;
+		}
+	}
+
+	if (twl_has_madc() && pdata->madc) {
+		pdev = platform_device_alloc("twl4030_madc", -1);
+		if (pdev) {
+			twl = &twl4030_modules[2];
+			pdev->dev.parent = &twl->client->dev;
+			device_init_wakeup(&pdev->dev, 1);
+			status = platform_device_add_data(pdev, pdata->madc,
+					sizeof(*pdata->madc));
+			if (status < 0) {
+				platform_device_put(pdev);
+				dev_dbg(&twl->client->dev,
+					"can't add madc data, %d\n",
+					status);
+				goto err;
+			}
+			status = platform_device_add(pdev);
+			if (status < 0) {
+				platform_device_put(pdev);
+				dev_dbg(&twl->client->dev,
+						"can't create madc dev, %d\n",
+						status);
+				goto err;
+			}
+		} else {
+			pr_debug("%s: can't alloc madc dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+			goto err;
+		}
+	}
+
+	if (twl_has_rtc()) {
+		twl = &twl4030_modules[3];
+
+		pdev = platform_device_alloc("twl4030_rtc", -1);
+		if (!pdev) {
+			pr_debug("%s: can't alloc rtc dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+		} else {
+			pdev->dev.parent = &twl->client->dev;
+			device_init_wakeup(&pdev->dev, 1);
+		}
+
+		/*
+		 * REVISIT platform_data here currently might use of
+		 * "msecure" line ... but for now we just expect board
+		 * setup to tell the chip "we are secure" at all times.
+		 * Eventually, Linux might become more aware of such
+		 * HW security concerns, and "least privilege".
+		 */
+
+		/* RTC module IRQ */
+		if (status == 0) {
+			struct resource	r = {
+				/* REVISIT don't hard-wire this stuff */
+				.start = TWL4030_PWRIRQ_RTC,
+				.flags = IORESOURCE_IRQ,
+			};
+
+			status = platform_device_add_resources(pdev, &r, 1);
+		}
+
+		if (status == 0)
+			status = platform_device_add(pdev);
+
+		if (status < 0) {
+			platform_device_put(pdev);
+			dev_dbg(&twl->client->dev,
+					"can't create rtc dev, %d\n",
+					status);
+			goto err;
+		}
+	}
+
+	if (twl_has_usb() && pdata->usb) {
+		twl = &twl4030_modules[0];
+
+		pdev = platform_device_alloc("twl4030_usb", -1);
+		if (!pdev) {
+			pr_debug("%s: can't alloc usb dev\n", DRIVER_NAME);
+			status = -ENOMEM;
+			goto err;
+		}
+
+		if (status == 0) {
+			pdev->dev.parent = &twl->client->dev;
+			device_init_wakeup(&pdev->dev, 1);
+			status = platform_device_add_data(pdev, pdata->usb,
+					sizeof(*pdata->usb));
+			if (status < 0) {
+				platform_device_put(pdev);
+				dev_dbg(&twl->client->dev,
+					"can't add usb data, %d\n",
+					status);
+				goto err;
+			}
+		}
+
+		if (status == 0) {
+			struct resource r = {
+				.start = TWL4030_PWRIRQ_USB_PRES,
+				.flags = IORESOURCE_IRQ,
+			};
+
+			status = platform_device_add_resources(pdev, &r, 1);
+		}
+
+		if (status == 0)
+			status = platform_device_add(pdev);
+
+		if (status < 0) {
+			platform_device_put(pdev);
+			dev_dbg(&twl->client->dev,
+					"can't create usb dev, %d\n",
+					status);
+		}
+	}
+
+err:
+	if (status)
+		pr_err("failed to add twl4030's children (status %d)\n", status);
+	return status;
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * These three functions initialize the on-chip clock framework,
+ * letting it generate the right frequencies for USB, MADC, and
+ * other purposes.
+ */
+static inline int __init protect_pm_master(void)
+{
+	int e = 0;
+
+	e = twl4030_i2c_write_u8(TWL4030_MODULE_PM_MASTER, KEY_LOCK,
+			R_PROTECT_KEY);
+	return e;
+}
+
+static inline int __init unprotect_pm_master(void)
+{
+	int e = 0;
+
+	e |= twl4030_i2c_write_u8(TWL4030_MODULE_PM_MASTER, KEY_UNLOCK1,
+			R_PROTECT_KEY);
+	e |= twl4030_i2c_write_u8(TWL4030_MODULE_PM_MASTER, KEY_UNLOCK2,
+			R_PROTECT_KEY);
+	return e;
+}
+
+static void __init clocks_init(void)
+{
+	int e = 0;
+	struct clk *osc;
+	u32 rate;
+	u8 ctrl = HFCLK_FREQ_26_MHZ;
+
+#if defined(CONFIG_ARCH_OMAP2) || defined(CONFIG_ARCH_OMAP3)
+	if (cpu_is_omap2430())
+		osc = clk_get(NULL, "osc_ck");
+	else
+		osc = clk_get(NULL, "osc_sys_ck");
+#else
+	/* REVISIT for non-OMAP systems, pass the clock rate from
+	 * board init code, using platform_data.
+	 */
+	osc = ERR_PTR(-EIO);
+#endif
+	if (IS_ERR(osc)) {
+		printk(KERN_WARNING "Skipping twl4030 internal clock init and "
+				"using bootloader value (unknown osc rate)\n");
+		return;
+	}
+
+	rate = clk_get_rate(osc);
+	clk_put(osc);
+
+	switch (rate) {
+	case 19200000:
+		ctrl = HFCLK_FREQ_19p2_MHZ;
+		break;
+	case 26000000:
+		ctrl = HFCLK_FREQ_26_MHZ;
+		break;
+	case 38400000:
+		ctrl = HFCLK_FREQ_38p4_MHZ;
+		break;
+	}
+
+	ctrl |= HIGH_PERF_SQ;
+	e |= unprotect_pm_master();
+	/* effect->MADC+USB ck en */
+	e |= twl4030_i2c_write_u8(TWL4030_MODULE_PM_MASTER, ctrl, R_CFG_BOOT);
+	e |= protect_pm_master();
+
+	if (e < 0)
+		pr_err("%s: clock init err [%d]\n", DRIVER_NAME, e);
+}
+
+/*----------------------------------------------------------------------*/
+
+/**
+ * twl4030_i2c_clear_isr - clear TWL4030 SIH ISR regs via read + write
+ * @mod_no: TWL4030 module number
+ * @reg: register index to clear
+ * @cor: value of the <module>_SIH_CTRL.COR bit (1 or 0)
+ *
+ * Either reads (cor == 1) or writes (cor == 0) to a TWL4030 interrupt
+ * status register to ensure that any prior interrupts are cleared.
+ * Returns the status from the I2C read operation.
+ */
+static int __init twl4030_i2c_clear_isr(u8 mod_no, u8 reg, u8 cor)
+{
+	u8 tmp;
+
+	return (cor) ? twl4030_i2c_read_u8(mod_no, &tmp, reg) :
+		twl4030_i2c_write_u8(mod_no, 0xff, reg);
+}
+
+/**
+ * twl4030_read_cor_bit - are TWL module ISRs cleared by reads or writes?
+ * @mod_no: TWL4030 module number
+ * @reg: register index to clear
+ *
+ * Returns 1 if the TWL4030 SIH interrupt status registers (ISRs) for
+ * the specified TWL module are cleared by reads, or 0 if cleared by
+ * writes.
+ */
+static int twl4030_read_cor_bit(u8 mod_no, u8 reg)
+{
+	u8 tmp = 0;
+
+	WARN_ON(twl4030_i2c_read_u8(mod_no, &tmp, reg) < 0);
+
+	tmp &= TWL4030_SIH_CTRL_COR_MASK;
+	tmp >>= __ffs(TWL4030_SIH_CTRL_COR_MASK);
+
+	return tmp;
+}
+
+/**
+ * twl4030_mask_clear_intrs - mask and clear all TWL4030 interrupts
+ * @t: pointer to twl4030_mod_iregs array
+ * @t_sz: ARRAY_SIZE(t) (starting at 1)
+ *
+ * Mask all TWL4030 interrupt mask registers (IMRs) and clear all
+ * interrupt status registers (ISRs).  No return value, but will WARN if
+ * any I2C operations fail.
+ */
+static void __init twl4030_mask_clear_intrs(const struct twl4030_mod_iregs *t,
+					    const u8 t_sz)
+{
+	int i, j;
+
+	/*
+	 * N.B. - further efficiency is possible here.  Eight I2C
+	 * operations on BCI and GPIO modules are avoidable if I2C
+	 * burst read/write transactions were implemented.  Would
+	 * probably save about 1ms of boot time and a small amount of
+	 * power.
+	 */
+	for (i = 0; i < t_sz; i++) {
+		const struct twl4030_mod_iregs tmr = t[i];
+		int cor;
+
+		/* Are ISRs cleared by reads or writes? */
+		cor = twl4030_read_cor_bit(tmr.mod_no, tmr.sih_ctrl);
+
+		for (j = 0; j < tmr.reg_cnt; j++) {
+
+			/* Mask interrupts at the TWL4030 */
+			WARN_ON(twl4030_i2c_write_u8(tmr.mod_no, 0xff,
+						     tmr.imrs[j]) < 0);
+
+			/* Clear TWL4030 ISRs */
+			WARN_ON(twl4030_i2c_clear_isr(tmr.mod_no,
+						      tmr.isrs[j], cor) < 0);
+		}
+	}
+}
+
+
+static void twl_init_irq(int irq_num, unsigned irq_base, unsigned irq_end)
+{
+	int	i;
+
+	/*
+	 * Mask and clear all TWL4030 interrupts since initially we do
+	 * not have any TWL4030 module interrupt handlers present
+	 */
+	twl4030_mask_clear_intrs(twl4030_mod_regs,
+				 ARRAY_SIZE(twl4030_mod_regs));
+
+	twl4030_irq_base = irq_base;
+
+	/* install an irq handler for each of the PIH modules */
+	for (i = irq_base; i < irq_end; i++) {
+		set_irq_chip_and_handler(i, &twl4030_irq_chip,
+				do_twl4030_module_irq);
+		activate_irq(i);
+	}
+
+	/* install an irq handler to demultiplex the TWL4030 interrupt */
+	set_irq_data(irq_num, start_twl4030_irq_thread(irq_num));
+	set_irq_chained_handler(irq_num, do_twl4030_irq);
+}
+
+/*----------------------------------------------------------------------*/
+
+static int twl4030_remove(struct i2c_client *client)
+{
+	unsigned i;
+
+	/* FIXME undo twl_init_irq() */
+	if (twl4030_irq_base) {
+		dev_err(&client->dev, "can't yet clean up IRQs?\n");
+		return -ENOSYS;
+	}
+
+	for (i = 0; i < TWL4030_NUM_SLAVES; i++) {
+		struct twl4030_client	*twl = &twl4030_modules[i];
+
+		if (twl->client && twl->client != client)
+			i2c_unregister_device(twl->client);
+		twl4030_modules[i].client = NULL;
+	}
+	inuse = false;
+	return 0;
+}
+
+/* NOTE:  this driver only handles a single twl4030/tps659x0 chip */
+static int
+twl4030_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	int				status;
+	unsigned			i;
+	struct twl4030_platform_data	*pdata = client->dev.platform_data;
+
+	if (!pdata) {
+		dev_dbg(&client->dev, "no platform data?\n");
+		return -EINVAL;
+	}
+
+	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C) == 0) {
+		dev_dbg(&client->dev, "can't talk I2C?\n");
+		return -EIO;
+	}
+
+	if (inuse || twl4030_irq_base) {
+		dev_dbg(&client->dev, "driver is already in use\n");
+		return -EBUSY;
+	}
+
+	for (i = 0; i < TWL4030_NUM_SLAVES; i++) {
+		struct twl4030_client	*twl = &twl4030_modules[i];
+
+		twl->address = client->addr + i;
+		if (i == 0)
+			twl->client = client;
+		else {
+			twl->client = i2c_new_dummy(client->adapter,
+					twl->address);
+			if (!twl->client) {
+				dev_err(&twl->client->dev,
+					"can't attach client %d\n", i);
+				status = -ENOMEM;
+				goto fail;
+			}
+			strlcpy(twl->client->name, id->name,
+					sizeof(twl->client->name));
+		}
+		mutex_init(&twl->xfer_lock);
+	}
+	inuse = true;
+
+	/* setup clock framework */
+	clocks_init();
+
+	/* Maybe init the T2 Interrupt subsystem */
+	if (client->irq
+			&& pdata->irq_base
+			&& pdata->irq_end > pdata->irq_base) {
+		twl_init_irq(client->irq, pdata->irq_base, pdata->irq_end);
+		dev_info(&client->dev, "IRQ %d chains IRQs %d..%d\n",
+				client->irq, pdata->irq_base, pdata->irq_end - 1);
+	}
+
+	status = add_children(pdata);
+fail:
+	if (status < 0)
+		twl4030_remove(client);
+	return status;
+}
+
+static const struct i2c_device_id twl4030_ids[] = {
+	{ "twl4030", 0 },	/* "Triton 2" */
+	{ "tps65950", 0 },	/* catalog version of twl4030 */
+	{ "tps65930", 0 },	/* fewer LDOs and DACs; no charger */
+	{ "tps65920", 0 },	/* fewer LDOs; no codec or charger */
+	{ "twl5030", 0 },	/* T2 updated */
+	{ /* end of list */ },
+};
+MODULE_DEVICE_TABLE(i2c, twl4030_ids);
+
+/* One Client Driver , 4 Clients */
+static struct i2c_driver twl4030_driver = {
+	.driver.name	= DRIVER_NAME,
+	.id_table	= twl4030_ids,
+	.probe		= twl4030_probe,
+	.remove		= twl4030_remove,
+};
+
+static int __init twl4030_init(void)
+{
+	return i2c_add_driver(&twl4030_driver);
+}
+subsys_initcall(twl4030_init);
+
+static void __exit twl4030_exit(void)
+{
+	i2c_del_driver(&twl4030_driver);
+}
+module_exit(twl4030_exit);
+
+MODULE_AUTHOR("Texas Instruments, Inc.");
+MODULE_DESCRIPTION("I2C Core interface for TWL4030");
+MODULE_LICENSE("GPL");