[RFC 1/2] powerpc/5200: add general purpose timer API for the MPC5200
Grant Likely
grant.likely at secretlab.ca
Sat Mar 7 08:12:32 EST 2009
From: Grant Likely <grant.likely at secretlab.ca>
This patch adds an interface for controlling the timer function of the
MPC5200 GPT devices.
Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
---
This probably isn't complete, but I wanted to get it out there and reviewed
before I commit to the design. Comments appreciated.
g.
arch/powerpc/include/asm/mpc52xx.h | 7 ++
arch/powerpc/platforms/52xx/mpc52xx_gpt.c | 132 +++++++++++++++++++++++++++--
2 files changed, 129 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/include/asm/mpc52xx.h b/arch/powerpc/include/asm/mpc52xx.h
index 81a2393..8273357 100644
--- a/arch/powerpc/include/asm/mpc52xx.h
+++ b/arch/powerpc/include/asm/mpc52xx.h
@@ -275,6 +275,13 @@ extern void mpc52xx_map_common_devices(void);
extern int mpc52xx_set_psc_clkdiv(int psc_id, int clkdiv);
extern void mpc52xx_restart(char *cmd);
+/* mpc52xx_gpt.c */
+struct mpc52xx_gpt_priv;
+extern struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq);
+extern int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
+ int continuous);
+extern void mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt);
+
/* mpc52xx_pic.c */
extern void mpc52xx_init_irq(void);
extern unsigned int mpc52xx_get_irq(void);
diff --git a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
index bfbcd41..e9e040f 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
@@ -46,9 +46,12 @@
* the output mode. This driver does not change the output mode setting.
*/
+#include <linux/device.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
@@ -68,16 +71,21 @@ MODULE_LICENSE("GPL");
* @irqhost: Pointer to irq_host instance; used when IRQ mode is supported
*/
struct mpc52xx_gpt_priv {
+ struct list_head list; /* List of all GPT devices */
struct device *dev;
struct mpc52xx_gpt __iomem *regs;
spinlock_t lock;
struct irq_host *irqhost;
+ u32 ipb_freq;
#if defined(CONFIG_GPIOLIB)
struct of_gpio_chip of_gc;
#endif
};
+LIST_HEAD(mpc52xx_gpt_list);
+DEFINE_MUTEX(mpc52xx_gpt_list_mutex);
+
#define MPC52xx_GPT_MODE_MS_MASK (0x07)
#define MPC52xx_GPT_MODE_MS_IC (0x01)
#define MPC52xx_GPT_MODE_MS_OC (0x02)
@@ -88,6 +96,9 @@ struct mpc52xx_gpt_priv {
#define MPC52xx_GPT_MODE_GPIO_OUT_LOW (0x20)
#define MPC52xx_GPT_MODE_GPIO_OUT_HIGH (0x30)
+#define MPC52xx_GPT_MODE_COUNTER_ENABLE (0x1000)
+#define MPC52xx_GPT_MODE_CONTINUOUS (0x0400)
+#define MPC52xx_GPT_MODE_OPEN_DRAIN (0x0200)
#define MPC52xx_GPT_MODE_IRQ_EN (0x0100)
#define MPC52xx_GPT_MODE_ICT_MASK (0x030000)
@@ -190,7 +201,7 @@ static int mpc52xx_gpt_irq_xlate(struct irq_host *h, struct device_node *ct,
dev_dbg(gpt->dev, "%s: flags=%i\n", __func__, intspec[0]);
- if ((intsize < 1) || (intspec[0] < 1) || (intspec[0] > 3)) {
+ if ((intsize < 1) || (intspec[0] > 3)) {
dev_err(gpt->dev, "bad irq specifier in %s\n", ct->full_name);
return -EINVAL;
}
@@ -211,13 +222,11 @@ mpc52xx_gpt_irq_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
{
int cascade_virq;
unsigned long flags;
-
- /* Only setup cascaded IRQ if device tree claims the GPT is
- * an interrupt controller */
- if (!of_find_property(node, "interrupt-controller", NULL))
- return;
+ u32 mode;
cascade_virq = irq_of_parse_and_map(node, 0);
+ if (!cascade_virq)
+ return;
gpt->irqhost = irq_alloc_host(node, IRQ_HOST_MAP_LINEAR, 1,
&mpc52xx_gpt_irq_ops, -1);
@@ -227,14 +236,16 @@ mpc52xx_gpt_irq_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
}
gpt->irqhost->host_data = gpt;
-
set_irq_data(cascade_virq, gpt);
set_irq_chained_handler(cascade_virq, mpc52xx_gpt_irq_cascade);
- /* Set to Input Capture mode */
+ /* If the GPT is currently disabled, then change it to be in Input
+ * Capture mode. If the mode is non-zero, then the pin could be
+ * already in use for something. */
spin_lock_irqsave(&gpt->lock, flags);
- clrsetbits_be32(&gpt->regs->mode, MPC52xx_GPT_MODE_MS_MASK,
- MPC52xx_GPT_MODE_MS_IC);
+ mode = in_be32(&gpt->regs->mode);
+ if ((mode & MPC52xx_GPT_MODE_MS_MASK) == 0)
+ out_be32(&gpt->regs->mode, mode | MPC52xx_GPT_MODE_MS_IC);
spin_unlock_irqrestore(&gpt->lock, flags);
dev_dbg(gpt->dev, "%s() complete. virq=%i\n", __func__, cascade_virq);
@@ -335,6 +346,102 @@ static void
mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *p, struct device_node *np) { }
#endif /* defined(CONFIG_GPIOLIB) */
+/***********************************************************************
+ * Timer API
+ */
+
+/**
+ * mpc52xx_gpt_from_irq - Return the GPT device associated with an IRQ number
+ * @irq: irq of timer.
+ */
+struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq)
+{
+ struct mpc52xx_gpt_priv *gpt;
+ struct list_head *pos;
+
+ /* Iterate over the list of timers looking for a matching device */
+ mutex_lock(&mpc52xx_gpt_list_mutex);
+ list_for_each(pos, &mpc52xx_gpt_list) {
+ gpt = container_of(pos, struct mpc52xx_gpt_priv, list);
+ if (gpt->irqhost && irq == irq_linear_revmap(gpt->irqhost, 0)) {
+ mutex_unlock(&mpc52xx_gpt_list_mutex);
+ return gpt;
+ }
+ }
+ mutex_unlock(&mpc52xx_gpt_list_mutex);
+
+ return NULL;
+}
+EXPORT_SYMBOL(mpc52xx_gpt_from_irq);
+
+/**
+ * mpc52xx_gpt_start_timer - Set and enable the GPT timer
+ * @gpt: Pointer to gpt private data structure
+ * @period: period of timer
+ * @continuous: set to 1 to make timer continuous free running
+ *
+ * An interrupt will be generated every time the timer fires
+ */
+int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
+ int continuous)
+{
+ u32 clear, set;
+ //u64 clocks;
+ u32 clocks;
+ u32 count, prescale;
+ unsigned long flags;
+
+ clear = MPC52xx_GPT_MODE_MS_MASK | MPC52xx_GPT_MODE_CONTINUOUS;
+ set = MPC52xx_GPT_MODE_MS_GPIO | MPC52xx_GPT_MODE_COUNTER_ENABLE;
+ if (continuous)
+ set |= MPC52xx_GPT_MODE_CONTINUOUS;
+
+ /* Determine the number of clocks in the requested period. 64 bit
+ * arithmatic is done here to preserve the precision until the value
+ * is scaled back down into the u32 range. Period is in 'ns', bus
+ * frequency is in Hz. */
+ //clocks = (u64)period * (u64)gpt->ipb_freq;
+ //clocks = clocks / 1000000000; /* Scale it down to ns range */
+ clocks = (period / 1000) * (gpt->ipb_freq / 1000000);
+
+ /* This device cannot handle a clock count greater than 32 bits */
+ if (clocks > 0xffffffff)
+ return -EINVAL;
+
+ /* Calculate the prescaler and count values from the clocks value.
+ * 'clocks' is the number of clock ticks in the period. The timer
+ * has 16 bit precision and a 16 bit prescaler. Prescaler is
+ * calculated by integer dividing the clocks by 0x10000 (shifting
+ * down 16 bits) to obtain the smallest possible divisor for clocks
+ * to get a 16 bit count value.
+ *
+ * Note: the prescale register is '1' based, not '0' based. ie. a
+ * value of '1' means divide the clock by one. 0xffff divides the
+ * clock by 0xffff. '0x0000' does not divide by zero, but wraps
+ * around and divides by 0x10000. That is why prescale must be
+ * a u32 variable, not a u16, for this calculation. */
+ prescale = (clocks >> 16) + 1;
+ count = clocks / prescale;
+ if (count > 0xffff)
+ pr_err("calculation error; count:%x prescale:%x clocks:%x\n",
+ count, prescale, clocks);
+
+ /* Set and enable the timer */
+ spin_lock_irqsave(&gpt->lock, flags);
+ out_be32(&gpt->regs->count, prescale << 16 | count);
+ clrsetbits_be32(&gpt->regs->mode, clear, set);
+ spin_unlock_irqrestore(&gpt->lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL(mpc52xx_gpt_start_timer);
+
+void mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt)
+{
+ clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_COUNTER_ENABLE);
+}
+EXPORT_SYMBOL(mpc52xx_gpt_stop_timer);
+
/* ---------------------------------------------------------------------
* of_platform bus binding code
*/
@@ -349,6 +456,7 @@ static int __devinit mpc52xx_gpt_probe(struct of_device *ofdev,
spin_lock_init(&gpt->lock);
gpt->dev = &ofdev->dev;
+ gpt->ipb_freq = mpc52xx_find_ipb_freq(ofdev->node);
gpt->regs = of_iomap(ofdev->node, 0);
if (!gpt->regs) {
kfree(gpt);
@@ -360,6 +468,10 @@ static int __devinit mpc52xx_gpt_probe(struct of_device *ofdev,
mpc52xx_gpt_gpio_setup(gpt, ofdev->node);
mpc52xx_gpt_irq_setup(gpt, ofdev->node);
+ mutex_lock(&mpc52xx_gpt_list_mutex);
+ list_add(&gpt->list, &mpc52xx_gpt_list);
+ mutex_unlock(&mpc52xx_gpt_list_mutex);
+
return 0;
}
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