411 lines
8.6 KiB
C
411 lines
8.6 KiB
C
/* arch/arm/plat-s3c/pwm.c
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*
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* Copyright (c) 2007 Ben Dooks
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* Copyright (c) 2008 Simtec Electronics
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* Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
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*
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* S3C series PWM device core
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <mach/irqs.h>
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#include <mach/map.h>
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#include <plat/devs.h>
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#include <plat/regs-timer.h>
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struct pwm_device {
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struct list_head list;
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struct platform_device *pdev;
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struct clk *clk_div;
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struct clk *clk;
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const char *label;
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unsigned int period_ns;
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unsigned int duty_ns;
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unsigned char tcon_base;
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unsigned char running;
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unsigned char use_count;
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unsigned char pwm_id;
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};
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#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
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static struct clk *clk_scaler[2];
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/* Standard setup for a timer block. */
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#define TIMER_RESOURCE_SIZE (1)
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#define TIMER_RESOURCE(_tmr, _irq) \
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(struct resource [TIMER_RESOURCE_SIZE]) { \
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[0] = { \
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.start = _irq, \
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.end = _irq, \
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.flags = IORESOURCE_IRQ \
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} \
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}
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#define DEFINE_S3C_TIMER(_tmr_no, _irq) \
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.name = "s3c24xx-pwm", \
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.id = _tmr_no, \
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.num_resources = TIMER_RESOURCE_SIZE, \
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.resource = TIMER_RESOURCE(_tmr_no, _irq), \
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/* since we already have an static mapping for the timer, we do not
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* bother setting any IO resource for the base.
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*/
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struct platform_device s3c_device_timer[] = {
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[0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
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[1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
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[2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
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[3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
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[4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
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};
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static inline int pwm_is_tdiv(struct pwm_device *pwm)
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{
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return clk_get_parent(pwm->clk) == pwm->clk_div;
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}
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static DEFINE_MUTEX(pwm_lock);
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static LIST_HEAD(pwm_list);
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struct pwm_device *pwm_request(int pwm_id, const char *label)
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{
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struct pwm_device *pwm;
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int found = 0;
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mutex_lock(&pwm_lock);
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list_for_each_entry(pwm, &pwm_list, list) {
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if (pwm->pwm_id == pwm_id) {
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found = 1;
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break;
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}
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}
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if (found) {
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if (pwm->use_count == 0) {
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pwm->use_count = 1;
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pwm->label = label;
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} else
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pwm = ERR_PTR(-EBUSY);
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} else
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pwm = ERR_PTR(-ENOENT);
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mutex_unlock(&pwm_lock);
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return pwm;
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}
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EXPORT_SYMBOL(pwm_request);
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void pwm_free(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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if (pwm->use_count) {
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pwm->use_count--;
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pwm->label = NULL;
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} else
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printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
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mutex_unlock(&pwm_lock);
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}
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EXPORT_SYMBOL(pwm_free);
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#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
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#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
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#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
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#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
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int pwm_enable(struct pwm_device *pwm)
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{
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unsigned long flags;
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unsigned long tcon;
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local_irq_save(flags);
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tcon = __raw_readl(S3C2410_TCON);
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tcon |= pwm_tcon_start(pwm);
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__raw_writel(tcon, S3C2410_TCON);
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local_irq_restore(flags);
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pwm->running = 1;
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return 0;
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}
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EXPORT_SYMBOL(pwm_enable);
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void pwm_disable(struct pwm_device *pwm)
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{
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unsigned long flags;
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unsigned long tcon;
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local_irq_save(flags);
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tcon = __raw_readl(S3C2410_TCON);
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tcon &= ~pwm_tcon_start(pwm);
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__raw_writel(tcon, S3C2410_TCON);
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local_irq_restore(flags);
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pwm->running = 0;
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}
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EXPORT_SYMBOL(pwm_disable);
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static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
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{
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unsigned long tin_parent_rate;
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unsigned int div;
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tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
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pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
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for (div = 2; div <= 16; div *= 2) {
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if ((tin_parent_rate / (div << 16)) < freq)
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return tin_parent_rate / div;
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}
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return tin_parent_rate / 16;
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}
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#define NS_IN_HZ (1000000000UL)
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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unsigned long tin_rate;
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unsigned long tin_ns;
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unsigned long period;
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unsigned long flags;
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unsigned long tcon;
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unsigned long tcnt;
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long tcmp;
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/* We currently avoid using 64bit arithmetic by using the
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* fact that anything faster than 1Hz is easily representable
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* by 32bits. */
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if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
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return -ERANGE;
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if (duty_ns > period_ns)
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return -EINVAL;
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if (period_ns == pwm->period_ns &&
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duty_ns == pwm->duty_ns)
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return 0;
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/* The TCMP and TCNT can be read without a lock, they're not
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* shared between the timers. */
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tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
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tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
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period = NS_IN_HZ / period_ns;
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pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
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duty_ns, period_ns, period);
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/* Check to see if we are changing the clock rate of the PWM */
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if (pwm->period_ns != period_ns) {
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if (pwm_is_tdiv(pwm)) {
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tin_rate = pwm_calc_tin(pwm, period);
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clk_set_rate(pwm->clk_div, tin_rate);
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} else
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tin_rate = clk_get_rate(pwm->clk);
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pwm->period_ns = period_ns;
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pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
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tin_ns = NS_IN_HZ / tin_rate;
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tcnt = period_ns / tin_ns;
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} else
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tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
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/* Note, counters count down */
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tcmp = duty_ns / tin_ns;
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tcmp = tcnt - tcmp;
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/* the pwm hw only checks the compare register after a decrement,
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so the pin never toggles if tcmp = tcnt */
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if (tcmp == tcnt)
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tcmp--;
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pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
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if (tcmp < 0)
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tcmp = 0;
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/* Update the PWM register block. */
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local_irq_save(flags);
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__raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
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__raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
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tcon = __raw_readl(S3C2410_TCON);
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tcon |= pwm_tcon_manulupdate(pwm);
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tcon |= pwm_tcon_autoreload(pwm);
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__raw_writel(tcon, S3C2410_TCON);
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tcon &= ~pwm_tcon_manulupdate(pwm);
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__raw_writel(tcon, S3C2410_TCON);
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local_irq_restore(flags);
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return 0;
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}
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EXPORT_SYMBOL(pwm_config);
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static int pwm_register(struct pwm_device *pwm)
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{
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pwm->duty_ns = -1;
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pwm->period_ns = -1;
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mutex_lock(&pwm_lock);
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list_add_tail(&pwm->list, &pwm_list);
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mutex_unlock(&pwm_lock);
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return 0;
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}
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static int s3c_pwm_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct pwm_device *pwm;
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unsigned long flags;
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unsigned long tcon;
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unsigned int id = pdev->id;
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int ret;
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if (id == 4) {
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dev_err(dev, "TIMER4 is currently not supported\n");
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return -ENXIO;
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}
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pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
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if (pwm == NULL) {
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dev_err(dev, "failed to allocate pwm_device\n");
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return -ENOMEM;
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}
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pwm->pdev = pdev;
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pwm->pwm_id = id;
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/* calculate base of control bits in TCON */
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pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
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pwm->clk = clk_get(dev, "pwm-tin");
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if (IS_ERR(pwm->clk)) {
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dev_err(dev, "failed to get pwm tin clk\n");
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ret = PTR_ERR(pwm->clk);
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goto err_alloc;
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}
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pwm->clk_div = clk_get(dev, "pwm-tdiv");
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if (IS_ERR(pwm->clk_div)) {
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dev_err(dev, "failed to get pwm tdiv clk\n");
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ret = PTR_ERR(pwm->clk_div);
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goto err_clk_tin;
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}
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local_irq_save(flags);
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tcon = __raw_readl(S3C2410_TCON);
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tcon |= pwm_tcon_invert(pwm);
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__raw_writel(tcon, S3C2410_TCON);
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local_irq_restore(flags);
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ret = pwm_register(pwm);
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if (ret) {
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dev_err(dev, "failed to register pwm\n");
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goto err_clk_tdiv;
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}
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pwm_dbg(pwm, "config bits %02x\n",
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(__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
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dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
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clk_get_rate(pwm->clk),
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clk_get_rate(pwm->clk_div),
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pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
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platform_set_drvdata(pdev, pwm);
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return 0;
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err_clk_tdiv:
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clk_put(pwm->clk_div);
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err_clk_tin:
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clk_put(pwm->clk);
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err_alloc:
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kfree(pwm);
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return ret;
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}
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static int s3c_pwm_remove(struct platform_device *pdev)
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{
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struct pwm_device *pwm = platform_get_drvdata(pdev);
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clk_put(pwm->clk_div);
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clk_put(pwm->clk);
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kfree(pwm);
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return 0;
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}
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static struct platform_driver s3c_pwm_driver = {
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.driver = {
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.name = "s3c24xx-pwm",
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.owner = THIS_MODULE,
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},
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.probe = s3c_pwm_probe,
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.remove = __devexit_p(s3c_pwm_remove),
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};
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static int __init pwm_init(void)
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{
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int ret;
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clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
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clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
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if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
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printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
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return -EINVAL;
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}
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ret = platform_driver_register(&s3c_pwm_driver);
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if (ret)
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printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
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return ret;
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}
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arch_initcall(pwm_init);
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