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From:   Srinivas Neeli <srinivas.neeli@xilinx.com>
To:     linus.walleij@linaro.org, bgolaszewski@baylibre.com,
        michal.simek@xilinx.com, shubhrajyoti.datta@xilinx.com,
        sgoud@xilinx.com
Cc:     linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, git@xilinx.com
Subject: [PATCH V2 1/3] gpio: xilinx: Add clock adaptation support
Date:   Thu, 23 Jul 2020 19:36:06 +0530
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Add support of clock adaptation for AXI GPIO driver.

Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
---
Changes in V2:
Add check for return value of platform_get_irq() API.
---
 drivers/gpio/gpio-xilinx.c | 111 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 109 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index 67f9f82e0db0..d103613e787a 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -14,6 +14,8 @@
 #include <linux/io.h>
 #include <linux/gpio/driver.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
+#include <linux/clk.h>
 
 /* Register Offset Definitions */
 #define XGPIO_DATA_OFFSET   (0x0)	/* Data register  */
@@ -38,6 +40,7 @@
  * @gpio_state: GPIO state shadow register
  * @gpio_dir: GPIO direction shadow register
  * @gpio_lock: Lock used for synchronization
+ * @clk: clock resource for this driver
  */
 struct xgpio_instance {
 	struct gpio_chip gc;
@@ -45,7 +48,8 @@ struct xgpio_instance {
 	unsigned int gpio_width[2];
 	u32 gpio_state[2];
 	u32 gpio_dir[2];
-	spinlock_t gpio_lock[2];
+	spinlock_t gpio_lock[2];	/* For serializing operations */
+	struct clk *clk;
 };
 
 static inline int xgpio_index(struct xgpio_instance *chip, int gpio)
@@ -256,6 +260,83 @@ static void xgpio_save_regs(struct xgpio_instance *chip)
 		       chip->gpio_dir[1]);
 }
 
+static int xgpio_request(struct gpio_chip *chip, unsigned int offset)
+{
+	int ret = pm_runtime_get_sync(chip->parent);
+
+	/*
+	 * If the device is already active pm_runtime_get() will return 1 on
+	 * success, but gpio_request still needs to return 0.
+	 */
+	return ret < 0 ? ret : 0;
+}
+
+static void xgpio_free(struct gpio_chip *chip, unsigned int offset)
+{
+	pm_runtime_put(chip->parent);
+}
+
+static int __maybe_unused xgpio_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct irq_data *data;
+	int irq = platform_get_irq(pdev, 0);
+
+	if (irq < 0) {
+		dev_info(&pdev->dev, "platform_get_irq returned %d\n", irq);
+		return irq;
+	}
+
+	data = irq_get_irq_data(irq);
+	if (!irqd_is_wakeup_set(data))
+		return pm_runtime_force_suspend(dev);
+
+	return 0;
+}
+
+static int __maybe_unused xgpio_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct irq_data *data;
+	int irq = platform_get_irq(pdev, 0);
+
+	if (irq < 0) {
+		dev_info(&pdev->dev, "platform_get_irq returned %d\n", irq);
+		return irq;
+	}
+
+	data = irq_get_irq_data(irq);
+
+	if (!irqd_is_wakeup_set(data))
+		return pm_runtime_force_resume(dev);
+
+	return 0;
+}
+
+static int __maybe_unused xgpio_runtime_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct xgpio_instance *gpio = platform_get_drvdata(pdev);
+
+	clk_disable(gpio->clk);
+
+	return 0;
+}
+
+static int __maybe_unused xgpio_runtime_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct xgpio_instance *gpio = platform_get_drvdata(pdev);
+
+	return clk_enable(gpio->clk);
+}
+
+static const struct dev_pm_ops xgpio_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(xgpio_suspend, xgpio_resume)
+	SET_RUNTIME_PM_OPS(xgpio_runtime_suspend,
+			   xgpio_runtime_resume, NULL)
+};
+
 /**
  * xgpio_of_probe - Probe method for the GPIO device.
  * @pdev: pointer to the platform device
@@ -324,6 +405,8 @@ static int xgpio_probe(struct platform_device *pdev)
 	chip->gc.direction_output = xgpio_dir_out;
 	chip->gc.get = xgpio_get;
 	chip->gc.set = xgpio_set;
+	chip->gc.request = xgpio_request;
+	chip->gc.free = xgpio_free;
 	chip->gc.set_multiple = xgpio_set_multiple;
 
 	chip->gc.label = dev_name(&pdev->dev);
@@ -334,15 +417,38 @@ static int xgpio_probe(struct platform_device *pdev)
 		return PTR_ERR(chip->regs);
 	}
 
+	chip->clk = devm_clk_get_optional(&pdev->dev, "s_axi_aclk");
+	if (IS_ERR(chip->clk)) {
+		if (PTR_ERR(chip->clk) != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "Input clock not found\n");
+		return PTR_ERR(chip->clk);
+	}
+	status = clk_prepare_enable(chip->clk);
+	if (status < 0) {
+		dev_err(&pdev->dev, "Failed to prepare clk\n");
+		return status;
+	}
+	pm_runtime_enable(&pdev->dev);
+	status = pm_runtime_get_sync(&pdev->dev);
+	if (status < 0)
+		goto err_unprepare_clk;
+
 	xgpio_save_regs(chip);
 
 	status = devm_gpiochip_add_data(&pdev->dev, &chip->gc, chip);
 	if (status) {
 		dev_err(&pdev->dev, "failed to add GPIO chip\n");
-		return status;
+		goto err_pm_put;
 	}
 
+	pm_runtime_put(&pdev->dev);
 	return 0;
+err_pm_put:
+	pm_runtime_put(&pdev->dev);
+err_unprepare_clk:
+	pm_runtime_disable(&pdev->dev);
+	clk_unprepare(chip->clk);
+	return status;
 }
 
 static const struct of_device_id xgpio_of_match[] = {
@@ -357,6 +463,7 @@ static struct platform_driver xgpio_plat_driver = {
 	.driver		= {
 			.name = "gpio-xilinx",
 			.of_match_table	= xgpio_of_match,
+			.pm = &xgpio_dev_pm_ops,
 	},
 };
 
-- 
2.7.4