linux/drivers/pwm/pwm-tegra.c
Philipp Zabel 6b03ef24ea pwm: tegra: Explicitly request exclusive reset control
Commit a53e35db70 ("reset: Ensure drivers are explicit when requesting
reset lines") started to transition the reset control request API calls
to explicitly state whether the driver needs exclusive or shared reset
control behavior. Convert all drivers requesting exclusive resets to the
explicit API call so the temporary transition helpers can be removed.

No functional changes.

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: linux-pwm@vger.kernel.org
Cc: linux-tegra@vger.kernel.org
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-08-21 08:53:07 +02:00

325 lines
7.7 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/pinctrl/consumer.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;
/* Maximum IP frequency for given SoCs */
unsigned long max_frequency;
};
struct tegra_pwm_chip {
struct pwm_chip chip;
struct device *dev;
struct clk *clk;
struct reset_control*rst;
unsigned long clk_rate;
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, hz;
unsigned long rate;
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 = DIV_ROUND_CLOSEST_ULL(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 = pc->clk_rate >> PWM_DUTY_WIDTH;
/* Consider precision in PWM_SCALE_WIDTH rate calculation */
hz = DIV_ROUND_CLOSEST_ULL(100ULL * NSEC_PER_SEC, period_ns);
rate = DIV_ROUND_CLOSEST_ULL(100ULL * rate, 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);
/* Set maximum frequency of the IP */
ret = clk_set_rate(pwm->clk, pwm->soc->max_frequency);
if (ret < 0) {
dev_err(&pdev->dev, "Failed to set max frequency: %d\n", ret);
return ret;
}
/*
* The requested and configured frequency may differ due to
* clock register resolutions. Get the configured frequency
* so that PWM period can be calculated more accurately.
*/
pwm->clk_rate = clk_get_rate(pwm->clk);
pwm->rst = devm_reset_control_get_exclusive(&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);
}
#ifdef CONFIG_PM_SLEEP
static int tegra_pwm_suspend(struct device *dev)
{
return pinctrl_pm_select_sleep_state(dev);
}
static int tegra_pwm_resume(struct device *dev)
{
return pinctrl_pm_select_default_state(dev);
}
#endif
static const struct tegra_pwm_soc tegra20_pwm_soc = {
.num_channels = 4,
.max_frequency = 48000000UL,
};
static const struct tegra_pwm_soc tegra186_pwm_soc = {
.num_channels = 1,
.max_frequency = 102000000UL,
};
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 const struct dev_pm_ops tegra_pwm_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(tegra_pwm_suspend, tegra_pwm_resume)
};
static struct platform_driver tegra_pwm_driver = {
.driver = {
.name = "tegra-pwm",
.of_match_table = tegra_pwm_of_match,
.pm = &tegra_pwm_pm_ops,
},
.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");