[PATCH v3] gpio: fxl6408: Add suspend/resume support

[Jisheng Zhang <jszhang@kernel.org>]

Currently, during suspend, do nothing; during resume, just sync the
regmap cache to hw regs.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---

since v2:
  - drop the reset pin support patch since no users now

since v1:
  -fix W=1 build error on nios2 platform

 drivers/gpio/gpio-fxl6408.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpio/gpio-fxl6408.c b/drivers/gpio/gpio-fxl6408.c
index 86ebc66b1104..165c48e9cb9c 100644
--- a/drivers/gpio/gpio-fxl6408.c
+++ b/drivers/gpio/gpio-fxl6408.c
@@ -43,6 +43,10 @@
 
 #define FXL6408_NGPIO			8
 
+struct fxl6408_chip {
+	struct regmap *regmap;
+};
+
 static const struct regmap_range rd_range[] = {
 	{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
 	{ FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
@@ -104,6 +108,7 @@ static int fxl6408_identify(struct device *dev, struct regmap *regmap)
 static int fxl6408_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
+	struct fxl6408_chip *chip;
 	int ret;
 	struct gpio_regmap_config gpio_config = {
 		.parent = dev,
@@ -114,6 +119,10 @@ static int fxl6408_probe(struct i2c_client *client)
 		.ngpio_per_reg = FXL6408_NGPIO,
 	};
 
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
 	gpio_config.regmap = devm_regmap_init_i2c(client, &regmap);
 	if (IS_ERR(gpio_config.regmap))
 		return dev_err_probe(dev, PTR_ERR(gpio_config.regmap),
@@ -123,6 +132,9 @@ static int fxl6408_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	chip->regmap = gpio_config.regmap;
+	i2c_set_clientdata(client, chip);
+
 	/* Disable High-Z of outputs, so that our OUTPUT updates actually take effect. */
 	ret = regmap_write(gpio_config.regmap, FXL6408_REG_OUTPUT_HIGH_Z, 0);
 	if (ret)
@@ -131,6 +143,16 @@ static int fxl6408_probe(struct i2c_client *client)
 	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
 }
 
+static int fxl6408_resume(struct device *dev)
+{
+	struct fxl6408_chip *chip = dev_get_drvdata(dev);
+
+	regcache_mark_dirty(chip->regmap);
+	return regcache_sync(chip->regmap);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(fxl6408_pm_ops, NULL, fxl6408_resume);
+
 static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {
 	{ .compatible = "fcs,fxl6408" },
 	{ }
@@ -146,6 +168,7 @@ MODULE_DEVICE_TABLE(i2c, fxl6408_id);
 static struct i2c_driver fxl6408_driver = {
 	.driver = {
 		.name	= "fxl6408",
+		.pm	= pm_sleep_ptr(&fxl6408_pm_ops),
 		.of_match_table = fxl6408_dt_ids,
 	},
 	.probe		= fxl6408_probe,
-- 
2.51.0