mfd: Add stmpe auto sleep feature

Some STMPE devices support entering sleep mode automatically on a
specified timeout of inactivity on the I2C bus with the host system.

Acked-by: Linus Walleij <[e-mail]>
Acked-by: Rabin Vincent <[e-mail]>
Signed-off-by: Sundar R Iyer <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/stmpe.c

···
 	},
 };
 
+/* supported autosleep timeout delay (in msecs) */
+static const int stmpe_autosleep_delay[] = {
+	4, 16, 32, 64, 128, 256, 512, 1024,
+};
+
+static int stmpe_round_timeout(int timeout)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(stmpe_autosleep_delay); i++) {
+		if (stmpe_autosleep_delay[i] >= timeout)
+			return i;
+	}
+
+	/*
+	 * requests for delays longer than supported should not return the
+	 * longest supported delay
+	 */
+	return -EINVAL;
+}
+
+static int stmpe_autosleep(struct stmpe *stmpe, int autosleep_timeout)
+{
+	int ret;
+
+	if (!stmpe->variant->enable_autosleep)
+		return -ENOSYS;
+
+	mutex_lock(&stmpe->lock);
+	ret = stmpe->variant->enable_autosleep(stmpe, autosleep_timeout);
+	mutex_unlock(&stmpe->lock);
+
+	return ret;
+}
+
+/*
+ * Both stmpe 1601/2403 support same layout for autosleep
+ */
+static int stmpe1601_autosleep(struct stmpe *stmpe,
+		int autosleep_timeout)
+{
+	int ret, timeout;
+
+	/* choose the best available timeout */
+	timeout = stmpe_round_timeout(autosleep_timeout);
+	if (timeout < 0) {
+		dev_err(stmpe->dev, "invalid timeout\n");
+		return timeout;
+	}
+
+	ret = __stmpe_set_bits(stmpe, STMPE1601_REG_SYS_CTRL2,
+			STMPE1601_AUTOSLEEP_TIMEOUT_MASK,
+			timeout);
+	if (ret < 0)
+		return ret;
+
+	return __stmpe_set_bits(stmpe, STMPE1601_REG_SYS_CTRL2,
+			STPME1601_AUTOSLEEP_ENABLE,
+			STPME1601_AUTOSLEEP_ENABLE);
+}
+
 static int stmpe1601_enable(struct stmpe *stmpe, unsigned int blocks,
 			    bool enable)
 {
···
 	.num_irqs	= STMPE1601_NR_INTERNAL_IRQS,
 	.enable		= stmpe1601_enable,
 	.get_altfunc	= stmpe1601_get_altfunc,
+	.enable_autosleep	= stmpe1601_autosleep,
 };
 
 /*
···
 	.num_irqs	= STMPE24XX_NR_INTERNAL_IRQS,
 	.enable		= stmpe24xx_enable,
 	.get_altfunc	= stmpe24xx_get_altfunc,
+	.enable_autosleep	= stmpe1601_autosleep, /* same as stmpe1601 */
 };
 
 static struct stmpe_variant_info *stmpe_variant_info[] = {
···
 static int __devinit stmpe_chip_init(struct stmpe *stmpe)
 {
 	unsigned int irq_trigger = stmpe->pdata->irq_trigger;
+	int autosleep_timeout = stmpe->pdata->autosleep_timeout;
 	struct stmpe_variant_info *variant = stmpe->variant;
 	u8 icr = STMPE_ICR_LSB_GIM;
 	unsigned int id;
···
 
 	if (stmpe->pdata->irq_invert_polarity)
 		icr ^= STMPE_ICR_LSB_HIGH;
+
+	if (stmpe->pdata->autosleep) {
+		ret = stmpe_autosleep(stmpe, autosleep_timeout);
+		if (ret)
+			return ret;
+	}
 
 	return stmpe_reg_write(stmpe, stmpe->regs[STMPE_IDX_ICR_LSB], icr);
 }

drivers/mfd/stmpe.h

···
  *		Called with the I/O lock held.
  * @get_altfunc: callback to get the alternate function number for the
  *		 specific block
+ * @enable_autosleep: callback to configure autosleep with specified timeout
  */
 struct stmpe_variant_info {
 	const char *name;
···
 	int num_irqs;
 	int (*enable)(struct stmpe *stmpe, unsigned int blocks, bool enable);
 	int (*get_altfunc)(struct stmpe *stmpe, enum stmpe_block block);
+	int (*enable_autosleep)(struct stmpe *stmpe, int autosleep_timeout);
 };
 
 #define STMPE_ICR_LSB_HIGH	(1 << 2)
···
 #define STMPE1601_NR_INTERNAL_IRQS	9
 
 #define STMPE1601_REG_SYS_CTRL			0x02
+#define STMPE1601_REG_SYS_CTRL2			0x03
 #define STMPE1601_REG_ICR_LSB			0x11
 #define STMPE1601_REG_IER_LSB			0x13
 #define STMPE1601_REG_ISR_MSB			0x14
···
 #define STMPE1601_SYS_CTRL_ENABLE_GPIO		(1 << 3)
 #define STMPE1601_SYS_CTRL_ENABLE_KPC		(1 << 1)
 #define STMPE1601_SYSCON_ENABLE_SPWM		(1 << 0)
+
+/* The 1601/2403 share the same masks */
+#define STMPE1601_AUTOSLEEP_TIMEOUT_MASK	(0x7)
+#define STPME1601_AUTOSLEEP_ENABLE		(1 << 3)
 
 /*
  * STMPE24xx

include/linux/mfd/stmpe.h

···
  * @blocks: bitmask of blocks to enable (use STMPE_BLOCK_*)
  * @irq_trigger: IRQ trigger to use for the interrupt to the host
  * @irq_invert_polarity: IRQ line is connected with reversed polarity
+ * @autosleep: bool to enable/disable stmpe autosleep
+ * @autosleep_timeout: inactivity timeout in milliseconds for autosleep
  * @irq_base: base IRQ number.  %STMPE_NR_IRQS irqs will be used, or
  *	      %STMPE_NR_INTERNAL_IRQS if the GPIO driver is not used.
  * @gpio: GPIO-specific platform data
···
 	int irq_base;
 	unsigned int irq_trigger;
 	bool irq_invert_polarity;
+	bool autosleep;
+	int autosleep_timeout;
 
 	struct stmpe_gpio_platform_data *gpio;
 	struct stmpe_keypad_platform_data *keypad;