Commit e5a06dc5 authored by Bart Tanghe's avatar Bart Tanghe Committed by Thierry Reding

pwm: Add BCM2835 PWM driver

Add PWM driver for Broadcom BCM2835 processor (Raspberry Pi)
Signed-off-by: default avatarBart Tanghe <bart.tanghe@thomasmore.be>
Acked-by: default avatarStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent cac7f242
BCM2835 PWM controller (Raspberry Pi controller)
Required properties:
- compatible: should be "brcm,bcm2835-pwm"
- reg: physical base address and length of the controller's registers
- clock: This clock defines the base clock frequency of the PWM hardware
system, the period and the duty_cycle of the PWM signal is a multiple of
the base period.
- #pwm-cells: Should be 2. See pwm.txt in this directory for a description of
the cells format.
Examples:
pwm@2020c000 {
compatible = "brcm,bcm2835-pwm";
reg = <0x2020c000 0x28>;
clocks = <&clk_pwm>;
#pwm-cells = <2>;
};
clocks {
....
clk_pwm: pwm {
compatible = "fixed-clock";
reg = <3>;
#clock-cells = <0>;
clock-frequency = <9200000>;
};
....
};
......@@ -71,6 +71,15 @@ config PWM_BCM_KONA
To compile this driver as a module, choose M here: the module
will be called pwm-bcm-kona.
config PWM_BCM2835
tristate "BCM2835 PWM support"
depends on ARCH_BCM2835
help
PWM framework driver for BCM2835 controller (Raspberry Pi)
To compile this driver as a module, choose M here: the module
will be called pwm-bcm2835.
config PWM_BFIN
tristate "Blackfin PWM support"
depends on BFIN_GPTIMERS
......
......@@ -4,6 +4,7 @@ obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o
......
/*
* Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#define PWM_CONTROL 0x000
#define PWM_CONTROL_SHIFT(x) ((x) * 8)
#define PWM_CONTROL_MASK 0xff
#define PWM_MODE 0x80 /* set timer in PWM mode */
#define PWM_ENABLE (1 << 0)
#define PWM_POLARITY (1 << 4)
#define PERIOD(x) (((x) * 0x10) + 0x10)
#define DUTY(x) (((x) * 0x10) + 0x14)
#define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */
struct bcm2835_pwm {
struct pwm_chip chip;
struct device *dev;
unsigned long scaler;
void __iomem *base;
struct clk *clk;
};
static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct bcm2835_pwm, chip);
}
static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
return 0;
}
static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
}
static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
if (period_ns <= MIN_PERIOD) {
dev_err(pc->dev, "period %d not supported, minimum %d\n",
period_ns, MIN_PERIOD);
return -EINVAL;
}
writel(duty_ns / pc->scaler, pc->base + DUTY(pwm->hwpwm));
writel(period_ns / pc->scaler, pc->base + PERIOD(pwm->hwpwm));
return 0;
}
static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
writel(value, pc->base + PWM_CONTROL);
return 0;
}
static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
}
static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
if (polarity == PWM_POLARITY_NORMAL)
value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
else
value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
writel(value, pc->base + PWM_CONTROL);
return 0;
}
static const struct pwm_ops bcm2835_pwm_ops = {
.request = bcm2835_pwm_request,
.free = bcm2835_pwm_free,
.config = bcm2835_pwm_config,
.enable = bcm2835_pwm_enable,
.disable = bcm2835_pwm_disable,
.set_polarity = bcm2835_set_polarity,
.owner = THIS_MODULE,
};
static int bcm2835_pwm_probe(struct platform_device *pdev)
{
struct bcm2835_pwm *pc;
struct resource *res;
int ret;
pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
if (!pc)
return -ENOMEM;
pc->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pc->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(pc->base))
return PTR_ERR(pc->base);
pc->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pc->clk)) {
dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
return PTR_ERR(pc->clk);
}
ret = clk_prepare_enable(pc->clk);
if (ret)
return ret;
pc->scaler = NSEC_PER_SEC / clk_get_rate(pc->clk);
pc->chip.dev = &pdev->dev;
pc->chip.ops = &bcm2835_pwm_ops;
pc->chip.npwm = 2;
platform_set_drvdata(pdev, pc);
ret = pwmchip_add(&pc->chip);
if (ret < 0)
goto add_fail;
return 0;
add_fail:
clk_disable_unprepare(pc->clk);
return ret;
}
static int bcm2835_pwm_remove(struct platform_device *pdev)
{
struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
clk_disable_unprepare(pc->clk);
return pwmchip_remove(&pc->chip);
}
static const struct of_device_id bcm2835_pwm_of_match[] = {
{ .compatible = "brcm,bcm2835-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
static struct platform_driver bcm2835_pwm_driver = {
.driver = {
.name = "bcm2835-pwm",
.of_match_table = bcm2835_pwm_of_match,
},
.probe = bcm2835_pwm_probe,
.remove = bcm2835_pwm_remove,
};
module_platform_driver(bcm2835_pwm_driver);
MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be");
MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
MODULE_LICENSE("GPL v2");
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