Cherry Trail SoCs have a built-in USB-role mux for switching between
the host and device controllers, rather then using an external mux
controller by a GPIO.

There is a driver using the mux-subsys to control this mux, this
commit adds support to the intel-int3496 driver to get a mux_controller
handle for the mux and set the mux through the mux-subsys rather then
through a GPIO.

Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
 drivers/extcon/Kconfig                |  1 +
 drivers/extcon/extcon-intel-int3496.c | 59 ++++++++++++++++++++++++++++++++++-
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index a7bca4207f44..7ab6acc9708a 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -45,6 +45,7 @@ config EXTCON_GPIO
 config EXTCON_INTEL_INT3496
        tristate "Intel INT3496 ACPI device extcon driver"
        depends on GPIOLIB && ACPI && (X86 || COMPILE_TEST)
+       select MULTIPLEXER
        help
          Say Y here to enable extcon support for USB OTG ports controlled by
          an Intel INT3496 ACPI device.
diff --git a/drivers/extcon/extcon-intel-int3496.c 
b/drivers/extcon/extcon-intel-int3496.c
index 1a45e745717d..cea9c9b1521c 100644
--- a/drivers/extcon/extcon-intel-int3496.c
+++ b/drivers/extcon/extcon-intel-int3496.c
@@ -23,8 +23,12 @@
 #include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/mux/consumer.h>
 #include <linux/platform_device.h>
 
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+
 #define INT3496_GPIO_USB_ID    0
 #define INT3496_GPIO_VBUS_EN   1
 #define INT3496_GPIO_USB_MUX   2
@@ -37,6 +41,8 @@ struct int3496_data {
        struct gpio_desc *gpio_usb_id;
        struct gpio_desc *gpio_vbus_en;
        struct gpio_desc *gpio_usb_mux;
+       struct mux_control *usb_mux;
+       bool usb_mux_set;
        int usb_id_irq;
 };
 
@@ -56,11 +62,31 @@ static const struct acpi_gpio_mapping 
acpi_int3496_default_gpios[] = {
        { },
 };
 
+static struct mux_lookup acpi_int3496_cht_mux_lookup[] = {
+       {
+               .provider = "intel_cht_usb_mux",
+               .dev_id   = "INT3496:00",
+               .mux_name = "usb-role-mux",
+       },
+};
+
+#define ICPU(model)    { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
+
+static const struct x86_cpu_id cht_cpu_ids[] = {
+       ICPU(INTEL_FAM6_ATOM_AIRMONT),          /* Braswell, Cherry Trail */
+       {}
+};
+
+static bool int3496_soc_has_mux(void)
+{
+       return x86_match_cpu(cht_cpu_ids);
+}
+
 static void int3496_do_usb_id(struct work_struct *work)
 {
        struct int3496_data *data =
                container_of(work, struct int3496_data, work.work);
-       int id = gpiod_get_value_cansleep(data->gpio_usb_id);
+       int ret, id = gpiod_get_value_cansleep(data->gpio_usb_id);
 
        /* id == 1: PERIPHERAL, id == 0: HOST */
        dev_dbg(data->dev, "Connected %s cable\n", id ? "PERIPHERAL" : "HOST");
@@ -72,6 +98,22 @@ static void int3496_do_usb_id(struct work_struct *work)
        if (!IS_ERR(data->gpio_usb_mux))
                gpiod_direction_output(data->gpio_usb_mux, id);
 
+       if (data->usb_mux) {
+               /*
+                * The mux framework expects multiple competing users, we must
+                * release our previous setting before applying the new one.
+                */
+               if (data->usb_mux_set)
+                       mux_control_deselect(data->usb_mux);
+
+               ret = mux_control_select(data->usb_mux,
+                                        id ? MUX_USB_DEVICE : MUX_USB_HOST);
+               if (ret)
+                       dev_err(data->dev, "Error setting mux: %d\n", ret);
+
+               data->usb_mux_set = ret == 0;
+       }
+
        if (!IS_ERR(data->gpio_vbus_en))
                gpiod_direction_output(data->gpio_vbus_en, !id);
 
@@ -107,6 +149,21 @@ static int int3496_probe(struct platform_device *pdev)
        data->dev = dev;
        INIT_DELAYED_WORK(&data->work, int3496_do_usb_id);
 
+       if (int3496_soc_has_mux()) {
+               mux_add_table(acpi_int3496_cht_mux_lookup,
+                             ARRAY_SIZE(acpi_int3496_cht_mux_lookup));
+               data->usb_mux = devm_mux_control_get(dev, "usb-role-mux");
+               /* Doing this here keeps our error handling clean. */
+               mux_remove_table(acpi_int3496_cht_mux_lookup,
+                                ARRAY_SIZE(acpi_int3496_cht_mux_lookup));
+               if (IS_ERR(data->usb_mux)) {
+                       ret = PTR_ERR(data->usb_mux);
+                       if (ret != -EPROBE_DEFER)
+                               dev_err(dev, "can't get mux: %d\n", ret);
+                       return ret;
+               }
+       }
+
        data->gpio_usb_id = devm_gpiod_get(dev, "id", GPIOD_IN);
        if (IS_ERR(data->gpio_usb_id)) {
                ret = PTR_ERR(data->gpio_usb_id);
-- 
2.13.5

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