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: Tony Prisk <linux@prisktech.co.nz> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
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17
Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
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17
Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
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@ -0,0 +1,17 @@
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VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
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Required properties:
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- compatible: should be "via,vt8500-pwm"
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- reg: physical base address and length of the controller's registers
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- #pwm-cells: should be 2. The first cell specifies the per-chip index
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of the PWM to use and the second cell is the period in nanoseconds.
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- clocks: phandle to the PWM source clock
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Example:
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pwm1: pwm@d8220000 {
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#pwm-cells = <2>;
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compatible = "via,vt8500-pwm";
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reg = <0xd8220000 0x1000>;
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clocks = <&clkpwm>;
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};
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@ -1,7 +1,8 @@
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/*
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* drivers/pwm/pwm-vt8500.c
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*
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* Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
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* Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
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* Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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@ -21,14 +22,24 @@
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <linux/delay.h>
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#include <linux/clk.h>
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#include <asm/div64.h>
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#define VT8500_NR_PWMS 4
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/of_address.h>
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/*
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* SoC architecture allocates register space for 4 PWMs but only
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* 2 are currently implemented.
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*/
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#define VT8500_NR_PWMS 2
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struct vt8500_chip {
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struct pwm_chip chip;
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void __iomem *base;
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struct clk *clk;
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};
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#define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
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@ -52,7 +63,7 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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unsigned long long c;
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unsigned long period_cycles, prescale, pv, dc;
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c = 25000000/2; /* wild guess --- need to implement clocks */
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c = clk_get_rate(vt8500->clk);
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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@ -85,8 +96,15 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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int err;
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struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
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err = clk_enable(vt8500->clk);
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if (err < 0)
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dev_err(chip->dev, "failed to enable clock\n");
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return err;
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};
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pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
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writel(5, vt8500->base + (pwm->hwpwm << 4));
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return 0;
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@ -98,6 +116,8 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
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writel(0, vt8500->base + (pwm->hwpwm << 4));
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clk_disable(vt8500->clk);
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}
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static struct pwm_ops vt8500_pwm_ops = {
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@ -107,12 +127,24 @@ static struct pwm_ops vt8500_pwm_ops = {
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.owner = THIS_MODULE,
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};
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static int __devinit pwm_probe(struct platform_device *pdev)
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static const struct of_device_id vt8500_pwm_dt_ids[] = {
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{ .compatible = "via,vt8500-pwm", },
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{ /* Sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
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static int vt8500_pwm_probe(struct platform_device *pdev)
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{
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struct vt8500_chip *chip;
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struct resource *r;
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struct device_node *np = pdev->dev.of_node;
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int ret;
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if (!np) {
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dev_err(&pdev->dev, "invalid devicetree node\n");
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return -EINVAL;
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}
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chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
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if (chip == NULL) {
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dev_err(&pdev->dev, "failed to allocate memory\n");
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@ -124,6 +156,12 @@ static int __devinit pwm_probe(struct platform_device *pdev)
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chip->chip.base = -1;
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chip->chip.npwm = VT8500_NR_PWMS;
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chip->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(chip->clk)) {
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dev_err(&pdev->dev, "clock source not specified\n");
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return PTR_ERR(chip->clk);
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}
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (r == NULL) {
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dev_err(&pdev->dev, "no memory resource defined\n");
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@ -131,18 +169,26 @@ static int __devinit pwm_probe(struct platform_device *pdev)
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}
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chip->base = devm_request_and_ioremap(&pdev->dev, r);
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if (chip->base == NULL)
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if (!chip->base)
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return -EADDRNOTAVAIL;
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ret = pwmchip_add(&chip->chip);
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if (ret < 0)
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ret = clk_prepare(chip->clk);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to prepare clock\n");
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return ret;
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}
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ret = pwmchip_add(&chip->chip);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to add PWM chip\n");
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return ret;
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}
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platform_set_drvdata(pdev, chip);
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return ret;
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}
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static int __devexit pwm_remove(struct platform_device *pdev)
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static int vt8500_pwm_remove(struct platform_device *pdev)
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{
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struct vt8500_chip *chip;
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@ -150,28 +196,22 @@ static int __devexit pwm_remove(struct platform_device *pdev)
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if (chip == NULL)
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return -ENODEV;
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clk_unprepare(chip->clk);
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return pwmchip_remove(&chip->chip);
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}
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static struct platform_driver pwm_driver = {
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static struct platform_driver vt8500_pwm_driver = {
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.probe = vt8500_pwm_probe,
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.remove = vt8500_pwm_remove,
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.driver = {
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.name = "vt8500-pwm",
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.owner = THIS_MODULE,
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.of_match_table = vt8500_pwm_dt_ids,
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},
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.probe = pwm_probe,
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.remove = __devexit_p(pwm_remove),
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};
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module_platform_driver(vt8500_pwm_driver);
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static int __init pwm_init(void)
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{
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return platform_driver_register(&pwm_driver);
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}
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arch_initcall(pwm_init);
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static void __exit pwm_exit(void)
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{
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platform_driver_unregister(&pwm_driver);
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}
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module_exit(pwm_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("VT8500 PWM Driver");
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MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
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MODULE_LICENSE("GPL v2");
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