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ARM: 5628/1: ep93xx: Introduce Pulse Width Modulator (PWM) driver

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The EP93xx features two PWMs (one on the EP9307) with the following
features:

  * Configurable dual output
  * Separate input clocks for each PWM output
  * 16-bit resolution
  * Programmable pulse width (duty cycle), interval (frequency), and
    polarity

This adds the necessary core support as well as the driver.  A sysfs
interface is provided to control the PWM outputs.

Signed-off-by: Matthieu Crapet <mcrapet@gmail.com>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Hartley Sweeten
2009-07-29 22:41:06 +01:00
committed by Russell King
parent 3aa7a9a3cf
commit ef12379f20
7 changed files with 492 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/misc/Kconfig
View File

@@ -233,6 +233,19 @@ config ISL29003
This driver can also be built as a module. If so, the module
will be called isl29003.
config EP93XX_PWM
tristate "EP93xx PWM support"
depends on ARCH_EP93XX
help
This option enables device driver support for the PWM channels
on the Cirrus EP93xx processors. The EP9307 chip only has one
PWM channel all the others have two, the second channel is an
alternate function of the EGPIO14 pin. A sysfs interface is
provided to control the PWM channels.
To compile this driver as a module, choose M here: the module will
be called ep93xx_pwm.
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"

1
drivers/misc/Makefile
View File

@@ -19,6 +19,7 @@ obj-$(CONFIG_SGI_XP) += sgi-xp/
obj-$(CONFIG_SGI_GRU) += sgi-gru/
obj-$(CONFIG_HP_ILO) += hpilo.o
obj-$(CONFIG_ISL29003) += isl29003.o
obj-$(CONFIG_EP93XX_PWM) += ep93xx_pwm.o
obj-$(CONFIG_C2PORT) += c2port/
obj-y += eeprom/
obj-y += cb710/

384
drivers/misc/ep93xx_pwm.c Normal file
View File

@@ -0,0 +1,384 @@
/*
* Simple PWM driver for EP93XX
*
* (c) Copyright 2009 Matthieu Crapet <mcrapet@gmail.com>
* (c) Copyright 2009 H Hartley Sweeten <hsweeten@visionengravers.com>
*
* 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; either version
* 2 of the License, or (at your option) any later version.
*
* EP9307 has only one channel:
* - PWMOUT
*
* EP9301/02/12/15 have two channels:
* - PWMOUT
* - PWMOUT1 (alternate function for EGPIO14)
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <mach/platform.h>
#define EP93XX_PWMx_TERM_COUNT 0x00
#define EP93XX_PWMx_DUTY_CYCLE 0x04
#define EP93XX_PWMx_ENABLE 0x08
#define EP93XX_PWMx_INVERT 0x0C
#define EP93XX_PWM_MAX_COUNT 0xFFFF
struct ep93xx_pwm {
void __iomem *mmio_base;
struct clk *clk;
u32 duty_percent;
};
static inline void ep93xx_pwm_writel(struct ep93xx_pwm *pwm,
unsigned int val, unsigned int off)
{
__raw_writel(val, pwm->mmio_base + off);
}
static inline unsigned int ep93xx_pwm_readl(struct ep93xx_pwm *pwm,
unsigned int off)
{
return __raw_readl(pwm->mmio_base + off);
}
static inline void ep93xx_pwm_write_tc(struct ep93xx_pwm *pwm, u16 value)
{
ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_TERM_COUNT);
}
static inline u16 ep93xx_pwm_read_tc(struct ep93xx_pwm *pwm)
{
return ep93xx_pwm_readl(pwm, EP93XX_PWMx_TERM_COUNT);
}
static inline void ep93xx_pwm_write_dc(struct ep93xx_pwm *pwm, u16 value)
{
ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_DUTY_CYCLE);
}
static inline void ep93xx_pwm_enable(struct ep93xx_pwm *pwm)
{
ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_ENABLE);
}
static inline void ep93xx_pwm_disable(struct ep93xx_pwm *pwm)
{
ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_ENABLE);
}
static inline int ep93xx_pwm_is_enabled(struct ep93xx_pwm *pwm)
{
return ep93xx_pwm_readl(pwm, EP93XX_PWMx_ENABLE) & 0x1;
}
static inline void ep93xx_pwm_invert(struct ep93xx_pwm *pwm)
{
ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_INVERT);
}
static inline void ep93xx_pwm_normal(struct ep93xx_pwm *pwm)
{
ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_INVERT);
}
static inline int ep93xx_pwm_is_inverted(struct ep93xx_pwm *pwm)
{
return ep93xx_pwm_readl(pwm, EP93XX_PWMx_INVERT) & 0x1;
}
/*
* /sys/devices/platform/ep93xx-pwm.N
* /min_freq read-only minimum pwm output frequency
* /max_req read-only maximum pwm output frequency
* /freq read-write pwm output frequency (0 = disable output)
* /duty_percent read-write pwm duty cycle percent (1..99)
* /invert read-write invert pwm output
*/
static ssize_t ep93xx_pwm_get_min_freq(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
unsigned long rate = clk_get_rate(pwm->clk);
return sprintf(buf, "%ld\n", rate / (EP93XX_PWM_MAX_COUNT + 1));
}
static ssize_t ep93xx_pwm_get_max_freq(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
unsigned long rate = clk_get_rate(pwm->clk);
return sprintf(buf, "%ld\n", rate / 2);
}
static ssize_t ep93xx_pwm_get_freq(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
if (ep93xx_pwm_is_enabled(pwm)) {
unsigned long rate = clk_get_rate(pwm->clk);
u16 term = ep93xx_pwm_read_tc(pwm);
return sprintf(buf, "%ld\n", rate / (term + 1));
} else {
return sprintf(buf, "disabled\n");
}
}
static ssize_t ep93xx_pwm_set_freq(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
long val;
int err;
err = strict_strtol(buf, 10, &val);
if (err)
return -EINVAL;
if (val == 0) {
ep93xx_pwm_disable(pwm);
} else if (val <= (clk_get_rate(pwm->clk) / 2)) {
u32 term, duty;
val = (clk_get_rate(pwm->clk) / val) - 1;
if (val > EP93XX_PWM_MAX_COUNT)
val = EP93XX_PWM_MAX_COUNT;
if (val < 1)
val = 1;
term = ep93xx_pwm_read_tc(pwm);
duty = ((val + 1) * pwm->duty_percent / 100) - 1;
/* If pwm is running, order is important */
if (val > term) {
ep93xx_pwm_write_tc(pwm, val);
ep93xx_pwm_write_dc(pwm, duty);
} else {
ep93xx_pwm_write_dc(pwm, duty);
ep93xx_pwm_write_tc(pwm, val);
}
if (!ep93xx_pwm_is_enabled(pwm))
ep93xx_pwm_enable(pwm);
} else {
return -EINVAL;
}
return count;
}
static ssize_t ep93xx_pwm_get_duty_percent(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
return sprintf(buf, "%d\n", pwm->duty_percent);
}
static ssize_t ep93xx_pwm_set_duty_percent(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
long val;
int err;
err = strict_strtol(buf, 10, &val);
if (err)
return -EINVAL;
if (val > 0 && val < 100) {
u32 term = ep93xx_pwm_read_tc(pwm);
ep93xx_pwm_write_dc(pwm, ((term + 1) * val / 100) - 1);
pwm->duty_percent = val;
return count;
}
return -EINVAL;
}
static ssize_t ep93xx_pwm_get_invert(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
return sprintf(buf, "%d\n", ep93xx_pwm_is_inverted(pwm));
}
static ssize_t ep93xx_pwm_set_invert(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct platform_device *pdev = to_platform_device(dev);
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
long val;
int err;
err = strict_strtol(buf, 10, &val);
if (err)
return -EINVAL;
if (val == 0)
ep93xx_pwm_normal(pwm);
else if (val == 1)
ep93xx_pwm_invert(pwm);
else
return -EINVAL;
return count;
}
static DEVICE_ATTR(min_freq, S_IRUGO, ep93xx_pwm_get_min_freq, NULL);
static DEVICE_ATTR(max_freq, S_IRUGO, ep93xx_pwm_get_max_freq, NULL);
static DEVICE_ATTR(freq, S_IWUGO | S_IRUGO,
ep93xx_pwm_get_freq, ep93xx_pwm_set_freq);
static DEVICE_ATTR(duty_percent, S_IWUGO | S_IRUGO,
ep93xx_pwm_get_duty_percent, ep93xx_pwm_set_duty_percent);
static DEVICE_ATTR(invert, S_IWUGO | S_IRUGO,
ep93xx_pwm_get_invert, ep93xx_pwm_set_invert);
static struct attribute *ep93xx_pwm_attrs[] = {
&dev_attr_min_freq.attr,
&dev_attr_max_freq.attr,
&dev_attr_freq.attr,
&dev_attr_duty_percent.attr,
&dev_attr_invert.attr,
NULL
};
static const struct attribute_group ep93xx_pwm_sysfs_files = {
.attrs = ep93xx_pwm_attrs,
};
static int __init ep93xx_pwm_probe(struct platform_device *pdev)
{
struct ep93xx_pwm *pwm;
struct resource *res;
int err;
err = ep93xx_pwm_acquire_gpio(pdev);
if (err)
return err;
pwm = kzalloc(sizeof(struct ep93xx_pwm), GFP_KERNEL);
if (!pwm) {
err = -ENOMEM;
goto fail_no_mem;
}
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
err = -ENXIO;
goto fail_no_mem_resource;
}
res = request_mem_region(res->start, resource_size(res), pdev->name);
if (res == NULL) {
err = -EBUSY;
goto fail_no_mem_resource;
}
pwm->mmio_base = ioremap(res->start, resource_size(res));
if (pwm->mmio_base == NULL) {
err = -ENXIO;
goto fail_no_ioremap;
}
err = sysfs_create_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
if (err)
goto fail_no_sysfs;
pwm->clk = clk_get(&pdev->dev, "pwm_clk");
if (IS_ERR(pwm->clk)) {
err = PTR_ERR(pwm->clk);
goto fail_no_clk;
}
pwm->duty_percent = 50;
platform_set_drvdata(pdev, pwm);
/* disable pwm at startup. Avoids zero value. */
ep93xx_pwm_disable(pwm);
ep93xx_pwm_write_tc(pwm, EP93XX_PWM_MAX_COUNT);
ep93xx_pwm_write_dc(pwm, EP93XX_PWM_MAX_COUNT / 2);
clk_enable(pwm->clk);
return 0;
fail_no_clk:
sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
fail_no_sysfs:
iounmap(pwm->mmio_base);
fail_no_ioremap:
release_mem_region(res->start, resource_size(res));
fail_no_mem_resource:
kfree(pwm);
fail_no_mem:
ep93xx_pwm_release_gpio(pdev);
return err;
}
static int __exit ep93xx_pwm_remove(struct platform_device *pdev)
{
struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ep93xx_pwm_disable(pwm);
clk_disable(pwm->clk);
clk_put(pwm->clk);
platform_set_drvdata(pdev, NULL);
sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
iounmap(pwm->mmio_base);
release_mem_region(res->start, resource_size(res));
kfree(pwm);
ep93xx_pwm_release_gpio(pdev);
return 0;
}
static struct platform_driver ep93xx_pwm_driver = {
.driver = {
.name = "ep93xx-pwm",
.owner = THIS_MODULE,
},
.remove = __exit_p(ep93xx_pwm_remove),
};
static int __init ep93xx_pwm_init(void)
{
return platform_driver_probe(&ep93xx_pwm_driver, ep93xx_pwm_probe);
}
static void __exit ep93xx_pwm_exit(void)
{
platform_driver_unregister(&ep93xx_pwm_driver);
}
module_init(ep93xx_pwm_init);
module_exit(ep93xx_pwm_exit);
MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
"H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_DESCRIPTION("EP93xx PWM driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ep93xx-pwm");