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47096d702c
Now that the JZ4740 and similar SoCs have a pinctrl driver, we rely on the pins being properly configured before the driver probes. One inherent problem of this new approach is that the pinctrl framework does not allow us to configure each pin on demand, when the various PWM channels are requested or released. For instance, the PWM channels can be configured from sysfs, which would require all PWM pins to be configured properly beforehand for the PWM function, eventually causing conflicts with other platform or board drivers. The proper solution here would be to modify the pwm-jz4740 driver to handle only one PWM channel, and create an instance of this driver for each one of the 8 PWM channels. Then, it could use the pinctrl framework to dynamically configure the PWM pin it controls. Until this can be done, the only jz4740 board supported upstream (Qi lb60) can configure all of its connected PWM pins in PWM function mode, since those are not used by other drivers nor by GPIOs on the board. Signed-off-by: Paul Cercueil <paul@crapouillou.net> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
178 lines
4.2 KiB
C
178 lines
4.2 KiB
C
/*
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* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
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* JZ4740 platform PWM support
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/gpio.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#include <asm/mach-jz4740/timer.h>
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#define NUM_PWM 8
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struct jz4740_pwm_chip {
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struct pwm_chip chip;
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struct clk *clk;
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};
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static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
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{
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return container_of(chip, struct jz4740_pwm_chip, chip);
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}
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static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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/*
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* Timers 0 and 1 are used for system tasks, so they are unavailable
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* for use as PWMs.
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*/
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if (pwm->hwpwm < 2)
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return -EBUSY;
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jz4740_timer_start(pwm->hwpwm);
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return 0;
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}
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static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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jz4740_timer_set_ctrl(pwm->hwpwm, 0);
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jz4740_timer_stop(pwm->hwpwm);
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}
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static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
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ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
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jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
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jz4740_timer_enable(pwm->hwpwm);
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return 0;
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}
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static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
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ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
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jz4740_timer_disable(pwm->hwpwm);
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jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
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}
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static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
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unsigned long long tmp;
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unsigned long period, duty;
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unsigned int prescaler = 0;
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uint16_t ctrl;
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bool is_enabled;
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tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
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do_div(tmp, 1000000000);
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period = tmp;
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while (period > 0xffff && prescaler < 6) {
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period >>= 2;
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++prescaler;
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}
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if (prescaler == 6)
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return -EINVAL;
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tmp = (unsigned long long)period * duty_ns;
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do_div(tmp, period_ns);
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duty = period - tmp;
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if (duty >= period)
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duty = period - 1;
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is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
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if (is_enabled)
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jz4740_pwm_disable(chip, pwm);
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jz4740_timer_set_count(pwm->hwpwm, 0);
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jz4740_timer_set_duty(pwm->hwpwm, duty);
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jz4740_timer_set_period(pwm->hwpwm, period);
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ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
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JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
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jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
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if (is_enabled)
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jz4740_pwm_enable(chip, pwm);
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return 0;
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}
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static const struct pwm_ops jz4740_pwm_ops = {
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.request = jz4740_pwm_request,
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.free = jz4740_pwm_free,
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.config = jz4740_pwm_config,
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.enable = jz4740_pwm_enable,
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.disable = jz4740_pwm_disable,
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.owner = THIS_MODULE,
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};
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static int jz4740_pwm_probe(struct platform_device *pdev)
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{
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struct jz4740_pwm_chip *jz4740;
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jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
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if (!jz4740)
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return -ENOMEM;
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jz4740->clk = devm_clk_get(&pdev->dev, "ext");
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if (IS_ERR(jz4740->clk))
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return PTR_ERR(jz4740->clk);
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jz4740->chip.dev = &pdev->dev;
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jz4740->chip.ops = &jz4740_pwm_ops;
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jz4740->chip.npwm = NUM_PWM;
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jz4740->chip.base = -1;
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platform_set_drvdata(pdev, jz4740);
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return pwmchip_add(&jz4740->chip);
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}
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static int jz4740_pwm_remove(struct platform_device *pdev)
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{
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struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
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return pwmchip_remove(&jz4740->chip);
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}
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static struct platform_driver jz4740_pwm_driver = {
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.driver = {
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.name = "jz4740-pwm",
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},
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.probe = jz4740_pwm_probe,
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.remove = jz4740_pwm_remove,
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};
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module_platform_driver(jz4740_pwm_driver);
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MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
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MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
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MODULE_ALIAS("platform:jz4740-pwm");
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MODULE_LICENSE("GPL");
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