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Date: Thu, 15 Jan 2015 17:40:37 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Nicolas Ferre <nicolas.ferre@...el.com>
CC: Boris Brezillon <boris.brezillon@...e-electrons.com>,
Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
Thomas Gleixner <tglx@...utronix.de>,
Samuel Ortiz <sameo@...ux.intel.com>,
Lee Jones <lee.jones@...aro.org>,
Wim Van Sebroeck <wim@...ana.be>,
Guenter Roeck <linux@...ck-us.net>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-watchdog@...r.kernel.org
Subject: Re: [PATCH v3 7/8] clocksource: atmel-st: use syscon/regmap
On 01/12/2015 04:37 PM, Alexandre Belloni wrote:
> The register range from the system timer is also used by the watchdog driver.
> Use a regmap to handle concurrent accesses.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> Acked-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> ---
> drivers/clocksource/timer-atmel-st.c | 103 +++++++++++++----------------------
> 1 file changed, 39 insertions(+), 64 deletions(-)
>
> diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c
> index ed0267f1c892..557389306be5 100644
> --- a/drivers/clocksource/timer-atmel-st.c
> +++ b/drivers/clocksource/timer-atmel-st.c
> @@ -24,20 +24,20 @@
> #include <linux/irq.h>
> #include <linux/clockchips.h>
> #include <linux/export.h>
> -#include <linux/of.h>
> -#include <linux/of_address.h>
> +#include <linux/mfd/atmel-st.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/of_irq.h>
> +#include <linux/regmap.h>
>
> #include <asm/mach/time.h>
> #include <asm/system_misc.h>
>
> -#include <mach/at91_st.h>
> -#include <mach/hardware.h>
> -
> static unsigned long last_crtr;
> static u32 irqmask;
> static struct clock_event_device clkevt;
> +static struct regmap *regmap_st;
>
> +#define AT91_SLOW_CLOCK 32768 /* DT compatibility */
> #define RM9200_TIMER_LATCH ((AT91_SLOW_CLOCK + HZ/2) / HZ)
>
> /*
> @@ -47,11 +47,11 @@ static struct clock_event_device clkevt;
> */
> static inline unsigned long read_CRTR(void)
> {
> - unsigned long x1, x2;
> + unsigned int x1, x2;
>
> - x1 = at91_st_read(AT91_ST_CRTR);
> + regmap_read(regmap_st, AT91_ST_CRTR, &x1);
> do {
> - x2 = at91_st_read(AT91_ST_CRTR);
> + regmap_read(regmap_st, AT91_ST_CRTR, &x2);
> if (x1 == x2)
> break;
> x1 = x2;
> @@ -64,7 +64,10 @@ static inline unsigned long read_CRTR(void)
> */
> static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id)
> {
> - u32 sr = at91_st_read(AT91_ST_SR) & irqmask;
> + u32 sr;
> +
> + regmap_read(regmap_st, AT91_ST_SR, &sr);
> + sr &= irqmask;
>
> /*
> * irqs should be disabled here, but as the irq is shared they are only
> @@ -97,7 +100,7 @@ static struct irqaction at91rm9200_timer_irq = {
> .name = "at91_tick",
> .flags = IRQF_SHARED | IRQF_TIMER | IRQF_IRQPOLL,
> .handler = at91rm9200_timer_interrupt,
> - .irq = NR_IRQS_LEGACY + AT91_ID_SYS,
> + .irq = 0,
> };
>
> static cycle_t read_clk32k(struct clocksource *cs)
> @@ -116,23 +119,25 @@ static struct clocksource clk32k = {
> static void
> clkevt32k_mode(enum clock_event_mode mode, struct clock_event_device *dev)
> {
> + unsigned int val;
> +
> /* Disable and flush pending timer interrupts */
> - at91_st_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_ALMS);
> - at91_st_read(AT91_ST_SR);
> + regmap_write(regmap_st, AT91_ST_IDR, AT91_ST_PITS | AT91_ST_ALMS);
> + regmap_read(regmap_st, AT91_ST_SR, &val);
>
> last_crtr = read_CRTR();
> switch (mode) {
> case CLOCK_EVT_MODE_PERIODIC:
> /* PIT for periodic irqs; fixed rate of 1/HZ */
> irqmask = AT91_ST_PITS;
> - at91_st_write(AT91_ST_PIMR, RM9200_TIMER_LATCH);
> + regmap_write(regmap_st, AT91_ST_PIMR, RM9200_TIMER_LATCH);
> break;
> case CLOCK_EVT_MODE_ONESHOT:
> /* ALM for oneshot irqs, set by next_event()
> * before 32 seconds have passed
> */
> irqmask = AT91_ST_ALMS;
> - at91_st_write(AT91_ST_RTAR, last_crtr);
> + regmap_write(regmap_st, AT91_ST_RTAR, last_crtr);
> break;
> case CLOCK_EVT_MODE_SHUTDOWN:
> case CLOCK_EVT_MODE_UNUSED:
> @@ -140,7 +145,7 @@ clkevt32k_mode(enum clock_event_mode mode, struct clock_event_device *dev)
> irqmask = 0;
> break;
> }
> - at91_st_write(AT91_ST_IER, irqmask);
> + regmap_write(regmap_st, AT91_ST_IER, irqmask);
> }
>
> static int
> @@ -148,6 +153,7 @@ clkevt32k_next_event(unsigned long delta, struct clock_event_device *dev)
> {
> u32 alm;
> int status = 0;
> + unsigned int val;
>
> BUG_ON(delta < 2);
>
> @@ -163,12 +169,12 @@ clkevt32k_next_event(unsigned long delta, struct clock_event_device *dev)
> alm = read_CRTR();
>
> /* Cancel any pending alarm; flush any pending IRQ */
> - at91_st_write(AT91_ST_RTAR, alm);
> - at91_st_read(AT91_ST_SR);
> + regmap_write(regmap_st, AT91_ST_RTAR, alm);
> + regmap_read(regmap_st, AT91_ST_SR, &val);
>
> /* Schedule alarm by writing RTAR. */
> alm += delta;
> - at91_st_write(AT91_ST_RTAR, alm);
> + regmap_write(regmap_st, AT91_ST_RTAR, alm);
>
> return status;
> }
> @@ -186,47 +192,8 @@ static void at91rm9200_restart(enum reboot_mode reboot_mode, const char *cmd)
> /*
> * Perform a hardware reset with the use of the Watchdog timer.
> */
> - at91_st_write(AT91_ST_WDMR, AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
> - at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
> -}
> -
> -void __iomem *at91_st_base;
> -EXPORT_SYMBOL_GPL(at91_st_base);
> -
> -static struct of_device_id at91rm9200_st_timer_ids[] = {
> - { .compatible = "atmel,at91rm9200-st" },
> - { /* sentinel */ }
> -};
> -
> -static int __init of_at91rm9200_st_init(void)
> -{
> - struct device_node *np;
> - int ret;
> -
> - np = of_find_matching_node(NULL, at91rm9200_st_timer_ids);
> - if (!np)
> - goto err;
> -
> - at91_st_base = of_iomap(np, 0);
> - if (!at91_st_base)
> - goto node_err;
> -
> - /* Get the interrupts property */
> - ret = irq_of_parse_and_map(np, 0);
> - if (!ret)
> - goto ioremap_err;
> - at91rm9200_timer_irq.irq = ret;
> -
> - of_node_put(np);
> -
> - return 0;
> -
> -ioremap_err:
> - iounmap(at91_st_base);
> -node_err:
> - of_node_put(np);
> -err:
> - return -EINVAL;
> + regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
> + regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
> }
>
> /*
> @@ -234,13 +201,21 @@ err:
> */
> static void __init atmel_st_timer_init(struct device_node *node)
> {
> - /* For device tree enabled device: initialize here */
> - of_at91rm9200_st_init();
> + unsigned int val;
> +
> + regmap_st = syscon_node_to_regmap(node);
> + if (IS_ERR(regmap_st))
> + panic(pr_fmt("Unable to get regmap\n"));
Is it possible to get ride of those panics ? IIRC, we discussed to not
panic when a timer was not initialized in case there is a definition for
another one.
>
> /* Disable all timer interrupts, and clear any pending ones */
> - at91_st_write(AT91_ST_IDR,
> + regmap_write(regmap_st, AT91_ST_IDR,
> AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
> - at91_st_read(AT91_ST_SR);
> + regmap_read(regmap_st, AT91_ST_SR, &val);
> +
> + /* Get the interrupts property */
> + at91rm9200_timer_irq.irq = irq_of_parse_and_map(node, 0);
> + if (!at91rm9200_timer_irq.irq)
> + panic(pr_fmt("Unable to get IRQ from DT\n"));
>
> /* Make IRQs happen for the system timer */
> setup_irq(at91rm9200_timer_irq.irq, &at91rm9200_timer_irq);
> @@ -249,7 +224,7 @@ static void __init atmel_st_timer_init(struct device_node *node)
> * directly for the clocksource and all clockevents, after adjusting
> * its prescaler from the 1 Hz default.
> */
> - at91_st_write(AT91_ST_RTMR, 1);
> + regmap_write(regmap_st, AT91_ST_RTMR, 1);
>
> /* Setup timer clockevent, with minimum of two ticks (important!!) */
> clkevt.cpumask = cpumask_of(0);
>
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