linux/drivers/pwm/pwm-tegra.c
Laxman Dewangan e9be88a2f0 pwm: tegra: Add support for Tegra186
Tegra186 has multiple PWM controllers with only one output instead of
one controller with four outputs in earlier SoC generations.

Add support for Tegra186 and detect the number of PWM outputs using
device tree match data.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-11 12:49:34 +02:00

286 lines
6.6 KiB
C

/*
* drivers/pwm/pwm-tegra.c
*
* Tegra pulse-width-modulation controller driver
*
* Copyright (c) 2010, NVIDIA Corporation.
* Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
*
* 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.
*
* 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pwm.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/reset.h>
#define PWM_ENABLE (1 << 31)
#define PWM_DUTY_WIDTH 8
#define PWM_DUTY_SHIFT 16
#define PWM_SCALE_WIDTH 13
#define PWM_SCALE_SHIFT 0
struct tegra_pwm_soc {
unsigned int num_channels;
};
struct tegra_pwm_chip {
struct pwm_chip chip;
struct device *dev;
struct clk *clk;
struct reset_control*rst;
void __iomem *regs;
const struct tegra_pwm_soc *soc;
};
static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct tegra_pwm_chip, chip);
}
static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
{
return readl(chip->regs + (num << 4));
}
static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
unsigned long val)
{
writel(val, chip->regs + (num << 4));
}
static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
unsigned long long c = duty_ns;
unsigned long rate, hz;
u32 val = 0;
int err;
/*
* Convert from duty_ns / period_ns to a fixed number of duty ticks
* per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
* nearest integer during division.
*/
c *= (1 << PWM_DUTY_WIDTH);
c += period_ns / 2;
do_div(c, period_ns);
val = (u32)c << PWM_DUTY_SHIFT;
/*
* Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
* cycles at the PWM clock rate will take period_ns nanoseconds.
*/
rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
hz = NSEC_PER_SEC / period_ns;
rate = (rate + (hz / 2)) / hz;
/*
* Since the actual PWM divider is the register's frequency divider
* field minus 1, we need to decrement to get the correct value to
* write to the register.
*/
if (rate > 0)
rate--;
/*
* Make sure that the rate will fit in the register's frequency
* divider field.
*/
if (rate >> PWM_SCALE_WIDTH)
return -EINVAL;
val |= rate << PWM_SCALE_SHIFT;
/*
* If the PWM channel is disabled, make sure to turn on the clock
* before writing the register. Otherwise, keep it enabled.
*/
if (!pwm_is_enabled(pwm)) {
err = clk_prepare_enable(pc->clk);
if (err < 0)
return err;
} else
val |= PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
/*
* If the PWM is not enabled, turn the clock off again to save power.
*/
if (!pwm_is_enabled(pwm))
clk_disable_unprepare(pc->clk);
return 0;
}
static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
int rc = 0;
u32 val;
rc = clk_prepare_enable(pc->clk);
if (rc < 0)
return rc;
val = pwm_readl(pc, pwm->hwpwm);
val |= PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
return 0;
}
static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
u32 val;
val = pwm_readl(pc, pwm->hwpwm);
val &= ~PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
clk_disable_unprepare(pc->clk);
}
static const struct pwm_ops tegra_pwm_ops = {
.config = tegra_pwm_config,
.enable = tegra_pwm_enable,
.disable = tegra_pwm_disable,
.owner = THIS_MODULE,
};
static int tegra_pwm_probe(struct platform_device *pdev)
{
struct tegra_pwm_chip *pwm;
struct resource *r;
int ret;
pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
if (!pwm)
return -ENOMEM;
pwm->soc = of_device_get_match_data(&pdev->dev);
pwm->dev = &pdev->dev;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pwm->regs = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(pwm->regs))
return PTR_ERR(pwm->regs);
platform_set_drvdata(pdev, pwm);
pwm->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pwm->clk))
return PTR_ERR(pwm->clk);
pwm->rst = devm_reset_control_get(&pdev->dev, "pwm");
if (IS_ERR(pwm->rst)) {
ret = PTR_ERR(pwm->rst);
dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
return ret;
}
reset_control_deassert(pwm->rst);
pwm->chip.dev = &pdev->dev;
pwm->chip.ops = &tegra_pwm_ops;
pwm->chip.base = -1;
pwm->chip.npwm = pwm->soc->num_channels;
ret = pwmchip_add(&pwm->chip);
if (ret < 0) {
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
reset_control_assert(pwm->rst);
return ret;
}
return 0;
}
static int tegra_pwm_remove(struct platform_device *pdev)
{
struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
unsigned int i;
int err;
if (WARN_ON(!pc))
return -ENODEV;
err = clk_prepare_enable(pc->clk);
if (err < 0)
return err;
for (i = 0; i < pc->chip.npwm; i++) {
struct pwm_device *pwm = &pc->chip.pwms[i];
if (!pwm_is_enabled(pwm))
if (clk_prepare_enable(pc->clk) < 0)
continue;
pwm_writel(pc, i, 0);
clk_disable_unprepare(pc->clk);
}
reset_control_assert(pc->rst);
clk_disable_unprepare(pc->clk);
return pwmchip_remove(&pc->chip);
}
static const struct tegra_pwm_soc tegra20_pwm_soc = {
.num_channels = 4,
};
static const struct tegra_pwm_soc tegra186_pwm_soc = {
.num_channels = 1,
};
static const struct of_device_id tegra_pwm_of_match[] = {
{ .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
{ .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
{ }
};
MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
static struct platform_driver tegra_pwm_driver = {
.driver = {
.name = "tegra-pwm",
.of_match_table = tegra_pwm_of_match,
},
.probe = tegra_pwm_probe,
.remove = tegra_pwm_remove,
};
module_platform_driver(tegra_pwm_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("NVIDIA Corporation");
MODULE_ALIAS("platform:tegra-pwm");