linux-kernel - [PATCH V3] gpio: mxc: add clock operation

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Date:   Tue, 22 May 2018 11:05:40 +0800
From:   Anson Huang <Anson.Huang@....com>
To:     linus.walleij@...aro.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Linux-imx@....com
Subject: [PATCH V3] gpio: mxc: add clock operation

Some i.MX SoCs have GPIO clock gates in CCM CCGR, such as
i.MX6SLL, need to enable clocks before accessing GPIO
registers, add optional clock operation for GPIO driver.

Signed-off-by: Anson Huang <Anson.Huang@....com>
---
changes since V2:
	remove the copyright change, since the change is already done by
	Fabio's patch [1/2] gpio: mxc: Switch to SPDX identifier, I redo
	the patch on top of it.
 drivers/gpio/gpio-mxc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
index 6a9dc61..2f28299 100644
--- a/drivers/gpio/gpio-mxc.c
+++ b/drivers/gpio/gpio-mxc.c
@@ -7,6 +7,7 @@
 // Authors: Daniel Mack, Juergen Beisert.
 // Copyright (C) 2004-2010 Freescale Semiconductor, Inc. All Rights Reserved.
 
+#include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -47,6 +48,7 @@ struct mxc_gpio_hwdata {
 struct mxc_gpio_port {
 	struct list_head node;
 	void __iomem *base;
+	struct clk *clk;
 	int irq;
 	int irq_high;
 	struct irq_domain *domain;
@@ -421,6 +423,17 @@ static int mxc_gpio_probe(struct platform_device *pdev)
 	if (port->irq < 0)
 		return port->irq;
 
+	/* the controller clock is optional */
+	port->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(port->clk))
+		port->clk = NULL;
+
+	err = clk_prepare_enable(port->clk);
+	if (err) {
+		dev_err(&pdev->dev, "Unable to enable clock.\n");
+		return err;
+	}
+
 	/* disable the interrupt and clear the status */
 	writel(0, port->base + GPIO_IMR);
 	writel(~0, port->base + GPIO_ISR);
@@ -489,6 +502,7 @@ static int mxc_gpio_probe(struct platform_device *pdev)
 out_irqdomain_remove:
 	irq_domain_remove(port->domain);
 out_bgio:
+	clk_disable_unprepare(port->clk);
 	dev_info(&pdev->dev, "%s failed with errno %d\n", __func__, err);
 	return err;
 }
-- 
2.7.4