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Commit 63e1ed23 authored by Tony Prisk's avatar Tony Prisk Committed by Thierry Reding
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pwm: vt8500: Update vt8500 PWM driver support 



This patch updates pwm-vt8500.c to support devicetree probing and
make use of the common clock subsystem.

A binding document describing the PWM controller found on
arch-vt8500 is also included.

Signed-off-by: default avatarTony Prisk <linux@prisktech.co.nz>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarThierry Reding <thierry.reding@avionic-design.de>
parent 8f0d8163

Documentation/devicetree/bindings/pwm/vt8500-pwm.txt

0 → 100644
+17 −0
Original line number Diff line number Diff line 
VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller



Required properties:

- compatible: should be "via,vt8500-pwm"

- reg: physical base address and length of the controller's registers

- #pwm-cells: should be 2.  The first cell specifies the per-chip index

  of the PWM to use and the second cell is the period in nanoseconds.

- clocks: phandle to the PWM source clock



Example:



pwm1: pwm@d8220000 {

	#pwm-cells = <2>;

	compatible = "via,vt8500-pwm";

	reg = <0xd8220000 0x1000>;

	clocks = <&clkpwm>;

};

drivers/pwm/pwm-vt8500.c

+63 −23
Original line number Diff line number Diff line 
/*

 * drivers/pwm/pwm-vt8500.c

 *

 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>

 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>

 *

 * This software is licensed under the terms of the GNU General Public
@@ -21,14 +22,24 @@ 
#include <linux/io.h>

#include <linux/pwm.h>

#include <linux/delay.h>

#include <linux/clk.h>



#include <asm/div64.h>



#define VT8500_NR_PWMS 4

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/of_address.h>



/*

 * SoC architecture allocates register space for 4 PWMs but only

 * 2 are currently implemented.

 */

#define VT8500_NR_PWMS	2



struct vt8500_chip {

	struct pwm_chip chip;

	void __iomem *base;

	struct clk *clk;

};



#define to_vt8500_chip(chip)	container_of(chip, struct vt8500_chip, chip)
@@ -52,7 +63,7 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 
	unsigned long long c;

	unsigned long period_cycles, prescale, pv, dc;



	c = 25000000/2; /* wild guess --- need to implement clocks */

	c = clk_get_rate(vt8500->clk);

	c = c * period_ns;

	do_div(c, 1000000000);

	period_cycles = c;
@@ -85,8 +96,15 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 


static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)

{

	int err;

	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);



	err = clk_enable(vt8500->clk);

	if (err < 0)

		dev_err(chip->dev, "failed to enable clock\n");

		return err;

	};



	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));

	writel(5, vt8500->base + (pwm->hwpwm << 4));

	return 0;
@@ -98,6 +116,8 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 


	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));

	writel(0, vt8500->base + (pwm->hwpwm << 4));



	clk_disable(vt8500->clk);

}



static struct pwm_ops vt8500_pwm_ops = {
@@ -107,12 +127,24 @@ static struct pwm_ops vt8500_pwm_ops = { 
	.owner = THIS_MODULE,

};



static int __devinit pwm_probe(struct platform_device *pdev)

static const struct of_device_id vt8500_pwm_dt_ids[] = {

	{ .compatible = "via,vt8500-pwm", },

	{ /* Sentinel */ }

};

MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);



static int vt8500_pwm_probe(struct platform_device *pdev)

{

	struct vt8500_chip *chip;

	struct resource *r;

	struct device_node *np = pdev->dev.of_node;

	int ret;



	if (!np) {

		dev_err(&pdev->dev, "invalid devicetree node\n");

		return -EINVAL;

	}



	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);

	if (chip == NULL) {

		dev_err(&pdev->dev, "failed to allocate memory\n");
@@ -124,6 +156,12 @@ static int __devinit pwm_probe(struct platform_device *pdev) 
	chip->chip.base = -1;

	chip->chip.npwm = VT8500_NR_PWMS;



	chip->clk = devm_clk_get(&pdev->dev, NULL);

	if (IS_ERR(chip->clk)) {

		dev_err(&pdev->dev, "clock source not specified\n");

		return PTR_ERR(chip->clk);

	}



	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (r == NULL) {

		dev_err(&pdev->dev, "no memory resource defined\n");
@@ -131,18 +169,26 @@ static int __devinit pwm_probe(struct platform_device *pdev) 
	}



	chip->base = devm_request_and_ioremap(&pdev->dev, r);

	if (chip->base == NULL)

	if (!chip->base)

		return -EADDRNOTAVAIL;



	ret = clk_prepare(chip->clk);

	if (ret < 0) {

		dev_err(&pdev->dev, "failed to prepare clock\n");

		return ret;

	}



	ret = pwmchip_add(&chip->chip);

	if (ret < 0)

	if (ret < 0) {

		dev_err(&pdev->dev, "failed to add PWM chip\n");

		return ret;

	}



	platform_set_drvdata(pdev, chip);

	return ret;

}



static int __devexit pwm_remove(struct platform_device *pdev)

static int vt8500_pwm_remove(struct platform_device *pdev)

{

	struct vt8500_chip *chip;
@@ -150,28 +196,22 @@ static int __devexit pwm_remove(struct platform_device *pdev) 
	if (chip == NULL)

		return -ENODEV;



	clk_unprepare(chip->clk);



	return pwmchip_remove(&chip->chip);

}



static struct platform_driver pwm_driver = {

static struct platform_driver vt8500_pwm_driver = {

	.probe		= vt8500_pwm_probe,

	.remove		= vt8500_pwm_remove,

	.driver		= {

		.name	= "vt8500-pwm",

		.owner	= THIS_MODULE,

		.of_match_table = vt8500_pwm_dt_ids,

	},

	.probe		= pwm_probe,

	.remove		= __devexit_p(pwm_remove),

};

module_platform_driver(vt8500_pwm_driver);



static int __init pwm_init(void)

{

	return platform_driver_register(&pwm_driver);

}

arch_initcall(pwm_init);



static void __exit pwm_exit(void)

{

	platform_driver_unregister(&pwm_driver);

}

module_exit(pwm_exit);



MODULE_LICENSE("GPL");
 
MODULE_DESCRIPTION("VT8500 PWM Driver");

MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");

MODULE_LICENSE("GPL v2");