MIPS: Lantiq: Add more gpio drivers

The XWAY family allows to extend the number of gpios by using shift
registers or latches. This patch adds the 2 drivers needed for this. The
extended gpios are output only.

[ralf@linux-mips.org: Fixed ltq_stp_probe section() attributes.]

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralph Hempel <ralph.hempel@lantiq.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2258/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 126 insertions, 0 deletions

diff --git a/arch/mips/lantiq/xway/gpio_ebu.c b/arch/mips/lantiq/xway/gpio_ebu.c
new file mode 100644
index 000000000000..a479355abdb9
--- /dev/null
+++ b/arch/mips/lantiq/xway/gpio_ebu.c
@@ -0,0 +1,126 @@
+/*
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+
+#include <lantiq_soc.h>
+
+/*
+ * By attaching hardware latches to the EBU it is possible to create output
+ * only gpios. This driver configures a special memory address, which when
+ * written to outputs 16 bit to the latches.
+ */
+
+#define LTQ_EBU_BUSCON	0x1e7ff		/* 16 bit access, slowest timing */
+#define LTQ_EBU_WP	0x80000000	/* write protect bit */
+
+/* we keep a shadow value of the last value written to the ebu */
+static int ltq_ebu_gpio_shadow = 0x0;
+static void __iomem *ltq_ebu_gpio_membase;
+
+static void ltq_ebu_apply(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ebu_lock, flags);
+	ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
+	*((__u16 *)ltq_ebu_gpio_membase) = ltq_ebu_gpio_shadow;
+	ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static void ltq_ebu_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	if (value)
+		ltq_ebu_gpio_shadow |= (1 << offset);
+	else
+		ltq_ebu_gpio_shadow &= ~(1 << offset);
+	ltq_ebu_apply();
+}
+
+static int ltq_ebu_direction_output(struct gpio_chip *chip, unsigned offset,
+	int value)
+{
+	ltq_ebu_set(chip, offset, value);
+
+	return 0;
+}
+
+static struct gpio_chip ltq_ebu_chip = {
+	.label = "ltq_ebu",
+	.direction_output = ltq_ebu_direction_output,
+	.set = ltq_ebu_set,
+	.base = 72,
+	.ngpio = 16,
+	.can_sleep = 1,
+	.owner = THIS_MODULE,
+};
+
+static int ltq_ebu_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!res) {
+		dev_err(&pdev->dev, "failed to get memory resource\n");
+		return -ENOENT;
+	}
+
+	res = devm_request_mem_region(&pdev->dev, res->start,
+		resource_size(res), dev_name(&pdev->dev));
+	if (!res) {
+		dev_err(&pdev->dev, "failed to request memory resource\n");
+		return -EBUSY;
+	}
+
+	ltq_ebu_gpio_membase = devm_ioremap_nocache(&pdev->dev, res->start,
+		resource_size(res));
+	if (!ltq_ebu_gpio_membase) {
+		dev_err(&pdev->dev, "Failed to ioremap mem region\n");
+		return -ENOMEM;
+	}
+
+	/* grab the default shadow value passed form the platform code */
+	ltq_ebu_gpio_shadow = (unsigned int) pdev->dev.platform_data;
+
+	/* tell the ebu controller which memory address we will be using */
+	ltq_ebu_w32(pdev->resource->start | 0x1, LTQ_EBU_ADDRSEL1);
+
+	/* write protect the region */
+	ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
+
+	ret = gpiochip_add(&ltq_ebu_chip);
+	if (!ret)
+		ltq_ebu_apply();
+	return ret;
+}
+
+static struct platform_driver ltq_ebu_driver = {
+	.probe = ltq_ebu_probe,
+	.driver = {
+		.name = "ltq_ebu",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init ltq_ebu_init(void)
+{
+	int ret = platform_driver_register(&ltq_ebu_driver);
+
+	if (ret)
+		pr_info("ltq_ebu : Error registering platfom driver!");
+	return ret;
+}
+
+postcore_initcall(ltq_ebu_init);