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Date: Thu, 8 Jan 2009 11:07:11 +0100
From: "Davide Rizzo" <elpa.rizzo@...il.com>
To: linux-kernel@...r.kernel.org, hjk@...utronix.de, gregkh@...e.de,
ben-linux@...ff.org
Subject: [PATCH 2/2] Driver for user access to internal timer
Adds the function pwm_one_shot to the pwm interface, to use a timer to wait for
a short period and call a callback at the end. This is for ms range delays.
There is also the implementation for the Samsung S3C24xx platform.
Signed-off-by: Davide Rizzo <elpa-rizzo@...il.com>
---
diff -urNp linux-2.6.28/arch/arm/plat-s3c24xx/pwm.c
linux-2.6.28.elpa/arch/arm/plat-s3c24xx/pwm.c
--- linux-2.6.28/arch/arm/plat-s3c24xx/pwm.c 2008-12-25 00:26:37.000000000 +0100
+++ linux-2.6.28.elpa/arch/arm/plat-s3c24xx/pwm.c 2009-01-06
19:04:44.000000000 +0100
@@ -15,6 +15,7 @@
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/err.h>
+#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
@@ -22,6 +23,8 @@
#include <plat/devs.h>
#include <plat/regs-timer.h>
+#define DEV_NAME "s3c24xx-pwm"
+
struct pwm_device {
struct list_head list;
struct platform_device *pdev;
@@ -37,6 +40,11 @@ struct pwm_device {
unsigned char running;
unsigned char use_count;
unsigned char pwm_id;
+
+ /* For one-shot mode callback*/
+ int irq;
+ void (*expired)(struct pwm_device *, void *arg);
+ void *arg;
};
#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
@@ -57,7 +65,7 @@ static struct clk *clk_scaler[2];
}
#define DEFINE_S3C_TIMER(_tmr_no, _irq) \
- .name = "s3c24xx-pwm", \
+ .name = DEV_NAME, \
.id = _tmr_no, \
.num_resources = TIMER_RESOURCE_SIZE, \
.resource = TIMER_RESOURCE(_tmr_no, _irq), \
@@ -272,6 +280,88 @@ int pwm_config(struct pwm_device *pwm, i
EXPORT_SYMBOL(pwm_config);
+static irqreturn_t timer_isr(int irq, void *arg)
+{
+ struct pwm_device *pwm = arg;
+
+ if (pwm->expired) {
+ disable_irq(irq);
+ pwm_disable(pwm);
+ pwm->expired(pwm, pwm->arg);
+ pwm->expired = NULL;
+ }
+ return IRQ_HANDLED;
+}
+
+int pwm_one_shot(struct pwm_device *pwm, int timeout_ns,
+ void(*expired)(struct pwm_device *, void *arg), void *arg)
+{
+ unsigned long tin_rate;
+ unsigned long tin_ns;
+ unsigned long period;
+ unsigned long flags;
+ unsigned long tcon;
+ unsigned long tcnt;
+
+ /* We currently avoid using 64bit arithmetic by using the
+ * fact that anything faster than 1Hz is easily representable
+ * by 32bits. */
+
+ if (timeout_ns > NS_IN_HZ)
+ return -ERANGE;
+
+ /* The TCMP and TCNT can be read without a lock, they're not
+ * shared between the timers. */
+
+ tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
+
+ period = NS_IN_HZ / timeout_ns;
+
+ pwm_dbg(pwm, "one shot timeout_ns=%d\n", timeout_ns);
+
+ if (pwm_is_tdiv(pwm)) {
+ tin_rate = pwm_calc_tin(pwm, period);
+ clk_set_rate(pwm->clk_div, tin_rate);
+ } else
+ tin_rate = clk_get_rate(pwm->clk);
+
+ pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
+
+ tin_ns = NS_IN_HZ / tin_rate;
+ tcnt = timeout_ns / tin_ns;
+ /* Note, counters count down */
+
+ pwm_dbg(pwm, "tin_ns=%lu\n", tin_ns);
+
+ /* Update the PWM register block. */
+
+ local_irq_save(flags);
+
+ if (!pwm->expired)
+ enable_irq(pwm->irq);
+
+ __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
+
+ tcon = __raw_readl(S3C2410_TCON);
+ tcon |= pwm_tcon_manulupdate(pwm);
+ tcon &= ~pwm_tcon_autoreload(pwm);
+ tcon &= ~pwm_tcon_start(pwm);
+ __raw_writel(tcon, S3C2410_TCON);
+
+
+ pwm->expired = expired;
+ pwm->arg = arg;
+
+ tcon &= ~pwm_tcon_manulupdate(pwm);
+ tcon |= pwm_tcon_start(pwm);
+ __raw_writel(tcon, S3C2410_TCON);
+
+ local_irq_restore(flags);
+
+ return 0;
+}
+EXPORT_SYMBOL(pwm_one_shot);
+
static int pwm_register(struct pwm_device *pwm)
{
pwm->duty_ns = -1;
@@ -288,6 +378,7 @@ static int s3c_pwm_probe(struct platform
{
struct device *dev = &pdev->dev;
struct pwm_device *pwm;
+ struct resource *res;
unsigned long flags;
unsigned long tcon;
unsigned int id = pdev->id;
@@ -306,6 +397,22 @@ static int s3c_pwm_probe(struct platform
pwm->pdev = pdev;
pwm->pwm_id = id;
+ pwm->expired = NULL;
+
+ res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+ if (!res) {
+ dev_err(dev, "cannot get platform interrupt resource\n");
+ ret = -EBUSY;
+ goto err_getresources;
+ }
+ pwm->irq = res->start;
+ ret = request_irq(pwm->irq, timer_isr, IRQF_DISABLED,
+ DEV_NAME, pwm);
+ if (ret) {
+ dev_err(dev, "request_irq failed\n");
+ goto err_getirq;
+ }
+ disable_irq(pwm->irq);
/* calculate base of control bits in TCON */
pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
@@ -354,6 +461,10 @@ static int s3c_pwm_probe(struct platform
clk_put(pwm->clk_div);
err_clk_tin:
+ err_getresources:
+ free_irq(pwm->irq, DEV_NAME);
+
+ err_getirq:
clk_put(pwm->clk);
err_alloc:
@@ -365,6 +476,7 @@ static int s3c_pwm_remove(struct platfor
{
struct pwm_device *pwm = platform_get_drvdata(pdev);
+ free_irq(pwm->irq, DEV_NAME);
clk_put(pwm->clk_div);
clk_put(pwm->clk);
kfree(pwm);
@@ -374,7 +486,7 @@ static int s3c_pwm_remove(struct platfor
static struct platform_driver s3c_pwm_driver = {
.driver = {
- .name = "s3c24xx-pwm",
+ .name = DEV_NAME,
.owner = THIS_MODULE,
},
.probe = s3c_pwm_probe,
diff -urNp linux-2.6.28/include/linux/pwm.h
linux-2.6.28.elpa/include/linux/pwm.h
--- linux-2.6.28/include/linux/pwm.h 2008-12-25 00:26:37.000000000 +0100
+++ linux-2.6.28.elpa/include/linux/pwm.h 2009-01-06 19:35:19.000000000 +0100
@@ -19,6 +19,13 @@ void pwm_free(struct pwm_device *pwm);
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
/*
+ * pwm_one_shot - programs and starts a timer for one-shot operation
+ * when expired calls callback
+ */
+int pwm_one_shot(struct pwm_device *pwm, int timeout_ns,
+ void(*expired)(struct pwm_device *, void *arg), void *arg);
+
+/*
* pwm_enable - start a PWM output toggling
*/
int pwm_enable(struct pwm_device *pwm);
--
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