MFD: twl6040-codec: Handle thermal interrupt

When the TWL6040 temperature increases above a threshold that could
damage the device, a thermal interrupt and shutdown are started
automatically by the hardware.

The thermal event handling involves the following steps:
1. Forcefully deassert AUDPWRON to avoid keeping TWL6040 is
   Power-On state any longer
2. The event is notified to Android userspace through the switch
   class based mechanism so that further actions can be taken
3. While the device is in thermal shutdown, accesses to VDD/VSS
   registers will affect only register cache
4. Once the device has recovered from the thermal event, it will
   be put back to Power-On state regardless of the state requested
   by MFD clients:
   4.1. If clients have requested Power-On state, then the context
        of VDD/VSS registers is restored
   4.2. If clients have requested Sleep state, then the request will
        be honored. The additional Power-On -> Sleep transition is
        required to ensure that reference system is disabled after
        thermal shutdown
5. An additional notification is sent to Android userspace to inform
   about thermal shutdown recovery.

Change-Id: I38afa98fea03210312fc01ab0d2c6ab2a10c447d
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>
Signed-off-by: Chris Kelly <c-kelly@ti.com>

1 files changed, 98 insertions, 6 deletions

diff --git a/drivers/mfd/twl6040-codec.c b/drivers/mfd/twl6040-codec.c
index 5f0da1c..437e420 100644
--- a/drivers/mfd/twl6040-codec.c
+++ b/drivers/mfd/twl6040-codec.c
@@ -34,6 +34,8 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/twl6040-codec.h>
 
+static int twl6040_power(struct twl6040 *twl6040, int enable);
+
 int twl6040_get_reg_supply(unsigned int reg)
 {
 	if (reg > TWL6040_CACHEREGNUM)
@@ -100,7 +102,14 @@ int twl6040_reg_read(struct twl6040 *twl6040, unsigned int reg)
 	int ret;
 
 	mutex_lock(&twl6040->io_mutex);
-	ret = twl6040_i2c_read(twl6040, reg);
+	if (twl6040_reg_is_vio(reg) || likely(!twl6040->thshut)) {
+		ret = twl6040_i2c_read(twl6040, reg);
+	} else {
+		dev_warn(twl6040->dev,
+			"reg 0x%02x read from cache (thermal shutdown)\n",
+			reg);
+		ret = twl6040_cache_read(twl6040, reg);
+	}
 	mutex_unlock(&twl6040->io_mutex);
 
 	return ret;
@@ -132,7 +141,14 @@ int twl6040_reg_write(struct twl6040 *twl6040, unsigned int reg, u8 val)
 	int ret;
 
 	mutex_lock(&twl6040->io_mutex);
-	ret = twl6040_i2c_write(twl6040, reg, val);
+	if (twl6040_reg_is_vio(reg) || likely(!twl6040->thshut)) {
+		ret = twl6040_i2c_write(twl6040, reg, val);
+	} else {
+		dev_warn(twl6040->dev,
+			"reg 0x%02x write to cache (thermal shutdown)\n",
+			reg);
+		ret = twl6040_cache_write(twl6040, reg, val);
+	}
 	mutex_unlock(&twl6040->io_mutex);
 
 	return ret;
@@ -171,7 +187,14 @@ int twl6040_set_bits(struct twl6040 *twl6040, unsigned int reg, u8 mask)
 	int ret;
 
 	mutex_lock(&twl6040->io_mutex);
-	ret = twl6040_i2c_set_bits(twl6040, reg, mask);
+	if (twl6040_reg_is_vio(reg) || likely(!twl6040->thshut)) {
+		ret = twl6040_i2c_set_bits(twl6040, reg, mask);
+	} else {
+		dev_warn(twl6040->dev,
+			"reg 0x%02x access to cache (thermal shutdown)\n",
+			reg);
+		ret = twl6040_cache_set_bits(twl6040, reg, mask);
+	}
 	mutex_unlock(&twl6040->io_mutex);
 
 	return ret;
@@ -210,7 +233,14 @@ int twl6040_clear_bits(struct twl6040 *twl6040, unsigned int reg, u8 mask)
 	int ret;
 
 	mutex_lock(&twl6040->io_mutex);
-	ret = twl6040_i2c_clear_bits(twl6040, reg, mask);
+	if (twl6040_reg_is_vio(reg) || likely(!twl6040->thshut)) {
+		ret = twl6040_i2c_clear_bits(twl6040, reg, mask);
+	} else {
+		dev_warn(twl6040->dev,
+			"reg 0x%02x access to cache (thermal shutdown)\n",
+			reg);
+		ret = twl6040_cache_clear_bits(twl6040, reg, mask);
+	}
 	mutex_unlock(&twl6040->io_mutex);
 
 	return ret;
@@ -442,13 +472,54 @@ lppll_err:
 static irqreturn_t twl6040_naudint_handler(int irq, void *data)
 {
 	struct twl6040 *twl6040 = data;
-	u8 intid;
+	u8 intid, val;
 
 	intid = twl6040_reg_read(twl6040, TWL6040_REG_INTID);
 
 	if (intid & TWL6040_READYINT)
 		complete(&twl6040->ready);
 
+	if (intid & TWL6040_THINT) {
+		val = twl6040_reg_read(twl6040, TWL6040_REG_STATUS);
+		if (val & TWL6040_TSHUTDET) {
+			dev_err(twl6040->dev,
+				"thermal shutdown started\n");
+
+			twl6040->thshut = 1;
+
+			/*
+			 * power-down during thermal event keeps reference
+			 * system and temperature sensor active
+			 */
+			mutex_lock(&twl6040->mutex);
+			twl6040_power(twl6040, 0);
+			mutex_unlock(&twl6040->mutex);
+
+			twl6040_report_event(twl6040, TWL6040_THSHUT_EVENT);
+		} else {
+			dev_info(twl6040->dev,
+				"recovered from thermal shutdown\n");
+
+			twl6040->thshut = 0;
+
+			/*
+			 * power-up after recovered from thermal event can
+			 * be followed by power-down in case MFD is not
+			 * enabled so that reference system can be disabled
+			 */
+			mutex_lock(&twl6040->mutex);
+			twl6040_power(twl6040, 1);
+			if (!twl6040->power_count)
+				twl6040_power(twl6040, 0);
+			else
+				twl6040_restore_ctx(twl6040,
+						TWL6040_VDD_SUPPLY);
+			mutex_unlock(&twl6040->mutex);
+
+			twl6040_report_event(twl6040, TWL6040_THSHUT_RECOVERY);
+		}
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -631,6 +702,12 @@ int twl6040_enable(struct twl6040 *twl6040)
 {
 	int ret = 0;
 
+	if (twl6040->thshut) {
+		dev_warn(twl6040->dev,
+			"Power-up denied while in thermal shutdown\n");
+		return -EPERM;
+	}
+
 	mutex_lock(&twl6040->mutex);
 	if (!twl6040->power_count++)
 		ret = twl6040_power(twl6040, 1);
@@ -907,6 +984,15 @@ static int __devinit twl6040_probe(struct platform_device *pdev)
 				ret);
 			goto irq_err;
 		}
+
+		ret = twl6040_request_irq(twl6040, TWL6040_IRQ_TH,
+				twl6040_naudint_handler, 0,
+				"twl6040_irq_thermal", twl6040);
+		if (ret) {
+			dev_err(twl6040->dev, "THERMAL IRQ request failed: %d\n",
+				ret);
+			goto thirq_err;
+		}
 	}
 
 	/* dual-access registers controlled by I2C only */
@@ -957,6 +1043,9 @@ mfd_err:
 		pdata->put_ext_clk32k();
 clk32k_err:
 	if (naudint)
+		twl6040_free_irq(twl6040, TWL6040_IRQ_TH, twl6040);
+thirq_err:
+	if (naudint)
 		twl6040_free_irq(twl6040, TWL6040_IRQ_READY, twl6040);
 irq_err:
 	if (naudint)
@@ -982,7 +1071,10 @@ static int __devexit twl6040_remove(struct platform_device *pdev)
 
 	twl6040_disable(twl6040);
 
-	twl6040_free_irq(twl6040, TWL6040_IRQ_READY, twl6040);
+	if (naudint) {
+		twl6040_free_irq(twl6040, TWL6040_IRQ_READY, twl6040);
+		twl6040_free_irq(twl6040, TWL6040_IRQ_TH, twl6040);
+	}
 
 	if (gpio_is_valid(audpwron))
 		gpio_free(audpwron);