mfd: bd9576: Add IRQ support

BD9573 and BD9576 support set of "protection" interrupts for "fatal"
issues. Those lead to SOC reset as PMIC shuts the power outputs. Thus
there is no relevant IRQ handling for them.

Few "detection" interrupts were added to the BD9576 with the idea that
SOC could take some recovery-action before error gets unrecoverable.

Unfortunately the BD9576 interrupt logic was not re-evaluated. IRQs
are not designed to be properly acknowleged - and IRQ line is kept
active for whole duration of error condition (in comparison to
informing only about state change).

For above reason, do not consider missing IRQ as error.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

2 files changed, 147 insertions, 5 deletions

diff --git a/drivers/mfd/rohm-bd9576.c b/drivers/mfd/rohm-bd9576.c
index 2dbda1f401e2..6661a27d69a8 100644
--- a/drivers/mfd/rohm-bd9576.c
+++ b/drivers/mfd/rohm-bd9576.c
@@ -17,14 +17,30 @@
 #include <linux/regmap.h>
 #include <linux/types.h>
 
+enum {
+	BD957X_REGULATOR_CELL,
+	BD957X_WDT_CELL,
+};
+
+/*
+ * Due to the BD9576MUF nasty IRQ behaiour we don't always populate IRQs.
+ * These will be added to regulator resources only if IRQ information for the
+ * PMIC is populated in device-tree.
+ */
+static const struct resource bd9576_regulator_irqs[] = {
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_THERM, "bd9576-temp"),
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_OVD, "bd9576-ovd"),
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_UVD, "bd9576-uvd"),
+};
+
 static struct mfd_cell bd9573_mfd_cells[] = {
-	{ .name = "bd9573-regulator", },
-	{ .name = "bd9576-wdt", },
+	[BD957X_REGULATOR_CELL]	= { .name = "bd9573-regulator", },
+	[BD957X_WDT_CELL]	= { .name = "bd9576-wdt", },
 };
 
 static struct mfd_cell bd9576_mfd_cells[] = {
-	{ .name = "bd9576-regulator", },
-	{ .name = "bd9576-wdt", },
+	[BD957X_REGULATOR_CELL]	= { .name = "bd9576-regulator", },
+	[BD957X_WDT_CELL]	= { .name = "bd9576-wdt", },
 };
 
 static const struct regmap_range volatile_ranges[] = {
@@ -49,6 +65,29 @@ static struct regmap_config bd957x_regmap = {
 	.cache_type = REGCACHE_RBTREE,
 };
 
+static struct regmap_irq bd9576_irqs[] = {
+	REGMAP_IRQ_REG(BD9576_INT_THERM, 0, BD957X_MASK_INT_MAIN_THERM),
+	REGMAP_IRQ_REG(BD9576_INT_OVP, 0, BD957X_MASK_INT_MAIN_OVP),
+	REGMAP_IRQ_REG(BD9576_INT_SCP, 0, BD957X_MASK_INT_MAIN_SCP),
+	REGMAP_IRQ_REG(BD9576_INT_OCP, 0, BD957X_MASK_INT_MAIN_OCP),
+	REGMAP_IRQ_REG(BD9576_INT_OVD, 0, BD957X_MASK_INT_MAIN_OVD),
+	REGMAP_IRQ_REG(BD9576_INT_UVD, 0, BD957X_MASK_INT_MAIN_UVD),
+	REGMAP_IRQ_REG(BD9576_INT_UVP, 0, BD957X_MASK_INT_MAIN_UVP),
+	REGMAP_IRQ_REG(BD9576_INT_SYS, 0, BD957X_MASK_INT_MAIN_SYS),
+};
+
+static struct regmap_irq_chip bd9576_irq_chip = {
+	.name = "bd9576_irq",
+	.irqs = &bd9576_irqs[0],
+	.num_irqs = ARRAY_SIZE(bd9576_irqs),
+	.status_base = BD957X_REG_INT_MAIN_STAT,
+	.mask_base = BD957X_REG_INT_MAIN_MASK,
+	.ack_base = BD957X_REG_INT_MAIN_STAT,
+	.init_ack_masked = true,
+	.num_regs = 1,
+	.irq_reg_stride = 1,
+};
+
 static int bd957x_i2c_probe(struct i2c_client *i2c,
 			     const struct i2c_device_id *id)
 {
@@ -57,6 +96,8 @@ static int bd957x_i2c_probe(struct i2c_client *i2c,
 	struct mfd_cell *cells;
 	int num_cells;
 	unsigned long chip_type;
+	struct irq_domain *domain;
+	bool usable_irqs;
 
 	chip_type = (unsigned long)of_device_get_match_data(&i2c->dev);
 
@@ -64,10 +105,16 @@ static int bd957x_i2c_probe(struct i2c_client *i2c,
 	case ROHM_CHIP_TYPE_BD9576:
 		cells = bd9576_mfd_cells;
 		num_cells = ARRAY_SIZE(bd9576_mfd_cells);
+		usable_irqs = !!i2c->irq;
 		break;
 	case ROHM_CHIP_TYPE_BD9573:
 		cells = bd9573_mfd_cells;
 		num_cells = ARRAY_SIZE(bd9573_mfd_cells);
+		/*
+		 * BD9573 only supports fatal IRQs which we can not handle
+		 * because SoC is going to lose the power.
+		 */
+		usable_irqs = false;
 		break;
 	default:
 		dev_err(&i2c->dev, "Unknown device type");
@@ -80,8 +127,41 @@ static int bd957x_i2c_probe(struct i2c_client *i2c,
 		return PTR_ERR(regmap);
 	}
 
+	/*
+	 * BD9576 behaves badly. It kepts IRQ line asserted for the whole
+	 * duration of detected HW condition (like over temperature). So we
+	 * don't require IRQ to be populated.
+	 * If IRQ information is not given, then we mask all IRQs and do not
+	 * provide IRQ resources to regulator driver - which then just omits
+	 * the notifiers.
+	 */
+	if (usable_irqs) {
+		struct regmap_irq_chip_data *irq_data;
+		struct mfd_cell *regulators;
+
+		regulators = &bd9576_mfd_cells[BD957X_REGULATOR_CELL];
+		regulators->resources = bd9576_regulator_irqs;
+		regulators->num_resources = ARRAY_SIZE(bd9576_regulator_irqs);
+
+		ret = devm_regmap_add_irq_chip(&i2c->dev, regmap, i2c->irq,
+					       IRQF_ONESHOT, 0,
+					       &bd9576_irq_chip, &irq_data);
+		if (ret) {
+			dev_err(&i2c->dev, "Failed to add IRQ chip\n");
+			return ret;
+		}
+		domain = regmap_irq_get_domain(irq_data);
+	} else {
+		ret = regmap_update_bits(regmap, BD957X_REG_INT_MAIN_MASK,
+					 BD957X_MASK_INT_ALL,
+					 BD957X_MASK_INT_ALL);
+		if (ret)
+			return ret;
+		domain = NULL;
+	}
+
 	ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO, cells,
-				   num_cells, NULL, 0, NULL);
+				   num_cells, NULL, 0, domain);
 	if (ret)
 		dev_err(&i2c->dev, "Failed to create subdevices\n");
 
diff --git a/include/linux/mfd/rohm-bd957x.h b/include/linux/mfd/rohm-bd957x.h
index a631abb2c101..ddb396ff2da5 100644
--- a/include/linux/mfd/rohm-bd957x.h
+++ b/include/linux/mfd/rohm-bd957x.h
@@ -13,6 +13,55 @@ enum {
 	BD957X_VOUTS1,
 };
 
+/*
+ * The BD9576 has own IRQ 'blocks' for:
+ *  - I2C/thermal,
+ *  - Over voltage protection
+ *  - Short-circuit protection
+ *  - Over current protection
+ *  - Over voltage detection
+ *  - Under voltage detection
+ *  - Under voltage protection
+ *  - 'system interrupt'.
+ *
+ * Each of the blocks have a status register giving more accurate IRQ source
+ * information - for example which of the regulators have over-voltage.
+ *
+ * On top of this, there is "main IRQ" status register where each bit indicates
+ * which of sub-blocks have active IRQs. Fine. That would fit regmap-irq main
+ * status handling. Except that:
+ *  - Only some sub-IRQs can be masked.
+ *  - The IRQ informs us about fault-condition, not when fault state changes.
+ *    The IRQ line it is kept asserted until the detected condition is acked
+ *    AND cleared in HW. This is annoying for IRQs like the one informing high
+ *    temperature because if IRQ is not disabled it keeps the CPU in IRQ
+ *    handling loop.
+ *
+ * For now we do just use the main-IRQ register as source for our IRQ
+ * information and bind the regmap-irq to this. We leave fine-grained sub-IRQ
+ * register handling to handlers in sub-devices. The regulator driver shall
+ * read which regulators are source for problem - or if the detected error is
+ * regulator temperature error. The sub-drivers do also handle masking of "sub-
+ * IRQs" if this is supported/needed.
+ *
+ * To overcome the problem with HW keeping IRQ asserted we do call
+ * disable_irq_nosync() from sub-device handler and add a delayed work to
+ * re-enable IRQ roughly 1 second later. This should keep our CPU out of
+ * busy-loop.
+ */
+#define IRQS_SILENT_MS			1000
+
+enum {
+	BD9576_INT_THERM,
+	BD9576_INT_OVP,
+	BD9576_INT_SCP,
+	BD9576_INT_OCP,
+	BD9576_INT_OVD,
+	BD9576_INT_UVD,
+	BD9576_INT_UVP,
+	BD9576_INT_SYS,
+};
+
 #define BD957X_REG_SMRB_ASSERT		0x15
 #define BD957X_REG_PMIC_INTERNAL_STAT	0x20
 #define BD957X_REG_INT_THERM_STAT	0x23
@@ -28,6 +77,19 @@ enum {
 #define BD957X_REG_INT_MAIN_STAT	0x30
 #define BD957X_REG_INT_MAIN_MASK	0x31
 
+#define UVD_IRQ_VALID_MASK		0x6F
+#define OVD_IRQ_VALID_MASK		0x2F
+
+#define BD957X_MASK_INT_MAIN_THERM	BIT(0)
+#define BD957X_MASK_INT_MAIN_OVP	BIT(1)
+#define BD957X_MASK_INT_MAIN_SCP	BIT(2)
+#define BD957X_MASK_INT_MAIN_OCP	BIT(3)
+#define BD957X_MASK_INT_MAIN_OVD	BIT(4)
+#define BD957X_MASK_INT_MAIN_UVD	BIT(5)
+#define BD957X_MASK_INT_MAIN_UVP	BIT(6)
+#define BD957X_MASK_INT_MAIN_SYS	BIT(7)
+#define BD957X_MASK_INT_ALL		0xff
+
 #define BD957X_REG_WDT_CONF		0x16
 
 #define BD957X_REG_POW_TRIGGER1		0x41