pinctrl/amd: save pin registers over suspend/resume

The touchpad in the Asus laptop models X505BA/BP and X542BA/BP is
unresponsive after suspend/resume. The following error appears during
resume:

  i2c_hid i2c-ELAN1300:00: failed to reset device.

The problem here is that i2c_hid does not notice the interrupt being
generated at this point, because the GPIO is no longer configured
for interrupts.

Fix this by saving pinctrl-amd pin registers during suspend and
restoring them at resume time.

Based on code from pinctrl-intel.

Cc: stable@vger.kernel.org
Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

2 files changed, 76 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinctrl-amd.c b/drivers/pinctrl/pinctrl-amd.c
index 38af1ec2df0c..3f6b34febbf1 100644
--- a/drivers/pinctrl/pinctrl-amd.c
+++ b/drivers/pinctrl/pinctrl-amd.c
@@ -36,6 +36,7 @@
 #include <linux/pinctrl/pinconf.h>
 #include <linux/pinctrl/pinconf-generic.h>
 
+#include "core.h"
 #include "pinctrl-utils.h"
 #include "pinctrl-amd.h"
 
@@ -725,6 +726,69 @@ static const struct pinconf_ops amd_pinconf_ops = {
         .pin_config_group_set = amd_pinconf_group_set,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static bool amd_gpio_should_save(struct amd_gpio *gpio_dev, unsigned int pin)
+{
+        const struct pin_desc *pd = pin_desc_get(gpio_dev->pctrl, pin);
+
+        if (!pd)
+                return false;
+
+        /*
+         * Only restore the pin if it is actually in use by the kernel (or
+         * by userspace).
+         */
+        if (pd->mux_owner || pd->gpio_owner ||
+            gpiochip_line_is_irq(&gpio_dev->gc, pin))
+                return true;
+
+        return false;
+}
+
+int amd_gpio_suspend(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct amd_gpio *gpio_dev = platform_get_drvdata(pdev);
+        struct pinctrl_desc *desc = gpio_dev->pctrl->desc;
+        int i;
+
+        for (i = 0; i < desc->npins; i++) {
+                int pin = desc->pins[i].number;
+
+                if (!amd_gpio_should_save(gpio_dev, pin))
+                        continue;
+
+                gpio_dev->saved_regs[i] = readl(gpio_dev->base + pin*4);
+        }
+
+        return 0;
+}
+
+int amd_gpio_resume(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct amd_gpio *gpio_dev = platform_get_drvdata(pdev);
+        struct pinctrl_desc *desc = gpio_dev->pctrl->desc;
+        int i;
+
+        for (i = 0; i < desc->npins; i++) {
+                int pin = desc->pins[i].number;
+
+                if (!amd_gpio_should_save(gpio_dev, pin))
+                        continue;
+
+                writel(gpio_dev->saved_regs[i], gpio_dev->base + pin*4);
+        }
+
+        return 0;
+}
+
+static const struct dev_pm_ops amd_gpio_pm_ops = {
+        SET_LATE_SYSTEM_SLEEP_PM_OPS(amd_gpio_suspend,
+                                     amd_gpio_resume)
+};
+#endif
+
 static struct pinctrl_desc amd_pinctrl_desc = {
         .pins   = kerncz_pins,
         .npins = ARRAY_SIZE(kerncz_pins),
@@ -764,6 +828,14 @@ static int amd_gpio_probe(struct platform_device *pdev)
                 return irq_base;
         }
 
+#ifdef CONFIG_PM_SLEEP
+        gpio_dev->saved_regs = devm_kcalloc(&pdev->dev, amd_pinctrl_desc.npins,
+                                            sizeof(*gpio_dev->saved_regs),
+                                            GFP_KERNEL);
+        if (!gpio_dev->saved_regs)
+                return -ENOMEM;
+#endif
+
         gpio_dev->pdev = pdev;
         gpio_dev->gc.direction_input    = amd_gpio_direction_input;
         gpio_dev->gc.direction_output   = amd_gpio_direction_output;
@@ -853,6 +925,9 @@ static struct platform_driver amd_gpio_driver = {
         .driver         = {
                 .name   = "amd_gpio",
                 .acpi_match_table = ACPI_PTR(amd_gpio_acpi_match),
+#ifdef CONFIG_PM_SLEEP
+                .pm     = &amd_gpio_pm_ops,
+#endif
         },
         .probe          = amd_gpio_probe,
         .remove         = amd_gpio_remove,
diff --git a/drivers/pinctrl/pinctrl-amd.h b/drivers/pinctrl/pinctrl-amd.h
index 5b1cb965c767..8fa453a59da5 100644
--- a/drivers/pinctrl/pinctrl-amd.h
+++ b/drivers/pinctrl/pinctrl-amd.h
@@ -97,6 +97,7 @@ struct amd_gpio {
         unsigned int            hwbank_num;
         struct resource         *res;
         struct platform_device  *pdev;
+        u32                     *saved_regs;
 };
 
 /*  KERNCZ configuration*/