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pwm: add support for atmel-hlcdc-pwm device 

The HLCDC IP available in some Atmel SoCs (i.e. at91sam9x5, at91sam9n12
or sama5d3 families for instance) provides a PWM device.

This driver add support for a PWM chip exposing a single PWM device (which
will most likely be used to drive a backlight device).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Anthony Harivel <anthony.harivel@emtrion.de>
Tested-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Boris Brezillon 2014-10-07 15:38:14 +02:00 committed by Thierry Reding
parent e5a06dc5ac
commit 2b4984bef4
3 changed files with 271 additions and 0 deletions
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11
drivers/pwm/Kconfig
View File

@ -50,6 +50,17 @@ config PWM_ATMEL
To compile this driver as a module, choose M here: the module
will be called pwm-atmel.
config PWM_ATMEL_HLCDC_PWM
tristate "Atmel HLCDC PWM support"
depends on MFD_ATMEL_HLCDC
help
Generic PWM framework driver for the PWM output of the HLCDC
(Atmel High-end LCD Controller). This PWM output is mainly used
to control the LCD backlight.
To compile this driver as a module, choose M here: the module
will be called pwm-atmel-hlcdc.
config PWM_ATMEL_TCB
tristate "Atmel TC Block PWM support"
depends on ATMEL_TCLIB && OF

1
drivers/pwm/Makefile
View File

@ -2,6 +2,7 @@ obj-$(CONFIG_PWM) += core.o
obj-$(CONFIG_PWM_SYSFS) += sysfs.o
obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o

259
drivers/pwm/pwm-atmel-hlcdc.c Normal file
View File

@ -0,0 +1,259 @@
/*
* Copyright (C) 2014 Free Electrons
* Copyright (C) 2014 Atmel
*
* Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/mfd/atmel-hlcdc.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#define ATMEL_HLCDC_PWMCVAL_MASK GENMASK(15, 8)
#define ATMEL_HLCDC_PWMCVAL(x) (((x) << 8) & ATMEL_HLCDC_PWMCVAL_MASK)
#define ATMEL_HLCDC_PWMPOL BIT(4)
#define ATMEL_HLCDC_PWMPS_MASK GENMASK(2, 0)
#define ATMEL_HLCDC_PWMPS_MAX 0x6
#define ATMEL_HLCDC_PWMPS(x) ((x) & ATMEL_HLCDC_PWMPS_MASK)
struct atmel_hlcdc_pwm {
struct pwm_chip chip;
struct atmel_hlcdc *hlcdc;
struct clk *cur_clk;
};
static inline struct atmel_hlcdc_pwm *to_atmel_hlcdc_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct atmel_hlcdc_pwm, chip);
}
static int atmel_hlcdc_pwm_config(struct pwm_chip *c,
struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
struct atmel_hlcdc *hlcdc = chip->hlcdc;
struct clk *new_clk = hlcdc->slow_clk;
u64 pwmcval = duty_ns * 256;
unsigned long clk_freq;
u64 clk_period_ns;
u32 pwmcfg;
int pres;
clk_freq = clk_get_rate(new_clk);
clk_period_ns = (u64)NSEC_PER_SEC * 256;
do_div(clk_period_ns, clk_freq);
if (clk_period_ns > period_ns) {
new_clk = hlcdc->sys_clk;
clk_freq = clk_get_rate(new_clk);
clk_period_ns = (u64)NSEC_PER_SEC * 256;
do_div(clk_period_ns, clk_freq);
}
for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++)
if ((clk_period_ns << pres) >= period_ns)
break;
if (pres > ATMEL_HLCDC_PWMPS_MAX)
return -EINVAL;
pwmcfg = ATMEL_HLCDC_PWMPS(pres);
if (new_clk != chip->cur_clk) {
u32 gencfg = 0;
int ret;
ret = clk_prepare_enable(new_clk);
if (ret)
return ret;
clk_disable_unprepare(chip->cur_clk);
chip->cur_clk = new_clk;
if (new_clk == hlcdc->sys_clk)
gencfg = ATMEL_HLCDC_CLKPWMSEL;
ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(0),
ATMEL_HLCDC_CLKPWMSEL, gencfg);
if (ret)
return ret;
}
do_div(pwmcval, period_ns);
/*
* The PWM duty cycle is configurable from 0/256 to 255/256 of the
* period cycle. Hence we can't set a duty cycle occupying the
* whole period cycle if we're asked to.
* Set it to 255 if pwmcval is greater than 256.
*/
if (pwmcval > 255)
pwmcval = 255;
pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
ATMEL_HLCDC_PWMCVAL_MASK |
ATMEL_HLCDC_PWMPS_MASK,
pwmcfg);
}
static int atmel_hlcdc_pwm_set_polarity(struct pwm_chip *c,
struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
struct atmel_hlcdc *hlcdc = chip->hlcdc;
u32 cfg = 0;
if (polarity == PWM_POLARITY_NORMAL)
cfg = ATMEL_HLCDC_PWMPOL;
return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
ATMEL_HLCDC_PWMPOL, cfg);
}
static int atmel_hlcdc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
{
struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
struct atmel_hlcdc *hlcdc = chip->hlcdc;
u32 status;
int ret;
ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PWM);
if (ret)
return ret;
while (true) {
ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
if (ret)
return ret;
if ((status & ATMEL_HLCDC_PWM) != 0)
break;
usleep_range(1, 10);
}
return 0;
}
static void atmel_hlcdc_pwm_disable(struct pwm_chip *c,
struct pwm_device *pwm)
{
struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
struct atmel_hlcdc *hlcdc = chip->hlcdc;
u32 status;
int ret;
ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS, ATMEL_HLCDC_PWM);
if (ret)
return;
while (true) {
ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
if (ret)
return;
if ((status & ATMEL_HLCDC_PWM) == 0)
break;
usleep_range(1, 10);
}
}
static const struct pwm_ops atmel_hlcdc_pwm_ops = {
.config = atmel_hlcdc_pwm_config,
.set_polarity = atmel_hlcdc_pwm_set_polarity,
.enable = atmel_hlcdc_pwm_enable,
.disable = atmel_hlcdc_pwm_disable,
.owner = THIS_MODULE,
};
static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct atmel_hlcdc_pwm *chip;
struct atmel_hlcdc *hlcdc;
int ret;
hlcdc = dev_get_drvdata(dev->parent);
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
ret = clk_prepare_enable(hlcdc->periph_clk);
if (ret)
return ret;
chip->hlcdc = hlcdc;
chip->chip.ops = &atmel_hlcdc_pwm_ops;
chip->chip.dev = dev;
chip->chip.base = -1;
chip->chip.npwm = 1;
chip->chip.of_xlate = of_pwm_xlate_with_flags;
chip->chip.of_pwm_n_cells = 3;
chip->chip.can_sleep = 1;
ret = pwmchip_add(&chip->chip);
if (ret) {
clk_disable_unprepare(hlcdc->periph_clk);
return ret;
}
platform_set_drvdata(pdev, chip);
return 0;
}
static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
{
struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
int ret;
ret = pwmchip_remove(&chip->chip);
if (ret)
return ret;
clk_disable_unprepare(chip->hlcdc->periph_clk);
return 0;
}
static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
{ .compatible = "atmel,hlcdc-pwm" },
{ /* sentinel */ },
};
static struct platform_driver atmel_hlcdc_pwm_driver = {
.driver = {
.name = "atmel-hlcdc-pwm",
.of_match_table = atmel_hlcdc_pwm_dt_ids,
},
.probe = atmel_hlcdc_pwm_probe,
.remove = atmel_hlcdc_pwm_remove,
};
module_platform_driver(atmel_hlcdc_pwm_driver);
MODULE_ALIAS("platform:atmel-hlcdc-pwm");
MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
MODULE_LICENSE("GPL v2");