i2c: mux/i801: Switch to use descriptor passing

This switches the i801 GPIO mux to use GPIO descriptors for
handling the GPIO lines. The previous hack which was reaching
inside the GPIO chips etc cannot live on. We pass descriptors
along with the GPIO mux device at creation instead.

The GPIO mux was only used by way of platform data with a
platform device from one place in the kernel: the i801 i2c bus
driver. Let's just associate the GPIO descriptor table with
the actual device like everyone else and dynamically create
a descriptor table passed along with the GPIO i2c mux.

This enables simplification of the GPIO i2c mux driver to
use only the descriptor API and the OF probe path gets
simplified in the process.

The i801 driver was registering the GPIO i2c mux with
PLATFORM_DEVID_AUTO which would make it hard to predict the
device name and assign the descriptor table properly, but
this seems to be a mistake to begin with: all of the
GPIO mux devices are hardcoded to look up GPIO lines from
the "gpio_ich" GPIO chip. If there are more than one mux,
there is certainly more than one gpio chip as well, and
then we have more serious problems. Switch to
PLATFORM_DEVID_NONE instead. There can be only one.

Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Peter Rosin <peda@axentia.se>
Cc: Jean Delvare <jdelvare@suse.com>
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[Removed a newline, suggested by Andy. /Peter]
Signed-off-by: Peter Rosin <peda@axentia.se>

1 files changed, 30 insertions, 7 deletions

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 679c6c41f64b..bf484cd775ec 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -107,7 +107,7 @@
 #include <linux/pm_runtime.h>
 
 #if IS_ENABLED(CONFIG_I2C_MUX_GPIO) && defined CONFIG_DMI
-#include <linux/gpio.h>
+#include <linux/gpio/machine.h>
 #include <linux/platform_data/i2c-mux-gpio.h>
 #endif
 
@@ -274,6 +274,7 @@ struct i801_priv {
 #if IS_ENABLED(CONFIG_I2C_MUX_GPIO) && defined CONFIG_DMI
 	const struct i801_mux_config *mux_drvdata;
 	struct platform_device *mux_pdev;
+	struct gpiod_lookup_table *lookup;
 #endif
 	struct platform_device *tco_pdev;
 
@@ -1258,7 +1259,8 @@ static int i801_add_mux(struct i801_priv *priv)
 	struct device *dev = &priv->adapter.dev;
 	const struct i801_mux_config *mux_config;
 	struct i2c_mux_gpio_platform_data gpio_data;
-	int err;
+	struct gpiod_lookup_table *lookup;
+	int err, i;
 
 	if (!priv->mux_drvdata)
 		return 0;
@@ -1270,17 +1272,36 @@ static int i801_add_mux(struct i801_priv *priv)
 	gpio_data.values = mux_config->values;
 	gpio_data.n_values = mux_config->n_values;
 	gpio_data.classes = mux_config->classes;
-	gpio_data.gpio_chip = mux_config->gpio_chip;
-	gpio_data.gpios = mux_config->gpios;
-	gpio_data.n_gpios = mux_config->n_gpios;
 	gpio_data.idle = I2C_MUX_GPIO_NO_IDLE;
 
-	/* Register the mux device */
+	/* Register GPIO descriptor lookup table */
+	lookup = devm_kzalloc(dev,
+			      struct_size(lookup, table, mux_config->n_gpios),
+			      GFP_KERNEL);
+	if (!lookup)
+		return -ENOMEM;
+	lookup->dev_id = "i2c-mux-gpio";
+	for (i = 0; i < mux_config->n_gpios; i++) {
+		lookup->table[i].chip_label = mux_config->gpio_chip;
+		lookup->table[i].chip_hwnum = mux_config->gpios[i];
+		lookup->table[i].con_id = "mux";
+	}
+	gpiod_add_lookup_table(lookup);
+	priv->lookup = lookup;
+
+	/*
+	 * Register the mux device, we use PLATFORM_DEVID_NONE here
+	 * because since we are referring to the GPIO chip by name we are
+	 * anyways in deep trouble if there is more than one of these
+	 * devices, and there should likely only be one platform controller
+	 * hub.
+	 */
 	priv->mux_pdev = platform_device_register_data(dev, "i2c-mux-gpio",
-				PLATFORM_DEVID_AUTO, &gpio_data,
+				PLATFORM_DEVID_NONE, &gpio_data,
 				sizeof(struct i2c_mux_gpio_platform_data));
 	if (IS_ERR(priv->mux_pdev)) {
 		err = PTR_ERR(priv->mux_pdev);
+		gpiod_remove_lookup_table(lookup);
 		priv->mux_pdev = NULL;
 		dev_err(dev, "Failed to register i2c-mux-gpio device\n");
 		return err;
@@ -1293,6 +1314,8 @@ static void i801_del_mux(struct i801_priv *priv)
 {
 	if (priv->mux_pdev)
 		platform_device_unregister(priv->mux_pdev);
+	if (priv->lookup)
+		gpiod_remove_lookup_table(priv->lookup);
 }
 
 static unsigned int i801_get_adapter_class(struct i801_priv *priv)