Commit 8011657b authored by Christian Daudt's avatar Christian Daudt Committed by John Stultz
Browse files

ARM: bcm281xx: Add timer driver (driver portion) 



This adds support for the Broadcom timer, used in the following SoCs:
BCM11130, BCM11140, BCM11351, BCM28145, BCM28155

Updates from V6:
- Split DT portion into a separate patch

Updates from V5:
- Rebase to latest arm-soc/for-next

Updates from V4:
- Switch code to use CLOCKSOURCE_OF_DECLARE

Updates from V3:
- Migrate to 3.9 timer framework updates

Updates from V2:
- prepend static fns + fields with kona_

Updates from V1:
- Rename bcm_timer.c to bcm_kona_timer.c
- Pull .h into bcm_kona_timer.c
- Make timers static
- Clean up comment block
- Switched to using clockevents_config_and_register
- Added an error to the get_timer loop if it repeats too much
- Added to Documentation/devicetree/bindings/arm/bcm/bcm,kona-timer.txt
- Added missing readl to timer_disable_and_clear

Note: bcm,kona-timer was kept as the 'compatible' field to make it
specific enough for when there are multiple bcm timers (bcm,timer is
too generic).

Signed-off-by: default avatarChristian Daudt <csd@broadcom.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarJohn Stultz <john.stultz@linaro.org>
Reviewed-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent dd5d70e8

arch/arm/mach-bcm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ config ARCH_BCM 
	select ARM_ERRATA_764369 if SMP

	select ARM_GIC

	select CPU_V7

	select CLKSRC_OF

	select GENERIC_CLOCKEVENTS

	select GENERIC_TIME

	select GPIO_BCM

arch/arm/mach-bcm/board_bcm.c

+2 −5
Original line number Diff line number Diff line
@@ -16,14 +16,11 @@ 
#include <linux/device.h>

#include <linux/platform_device.h>

#include <linux/irqchip.h>

#include <linux/clocksource.h>



#include <asm/mach/arch.h>

#include <asm/mach/time.h>



static void timer_init(void)

{

}





static void __init board_init(void)

{
@@ -35,7 +32,7 @@ static const char * const bcm11351_dt_compat[] = { "bcm,bcm11351", NULL, }; 


DT_MACHINE_START(BCM11351_DT, "Broadcom Application Processor")

	.init_irq = irqchip_init,

	.init_time = timer_init,

	.init_time = clocksource_of_init,

	.init_machine = board_init,

	.dt_compat = bcm11351_dt_compat,

MACHINE_END

drivers/clocksource/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ obj-$(CONFIG_ARCH_BCM2835) += bcm2835_timer.o 
obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o

obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o

obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o

obj-$(CONFIG_ARCH_BCM)		+= bcm_kona_timer.o



obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o

obj-$(CONFIG_CLKSRC_METAG_GENERIC)	+= metag_generic.o

drivers/clocksource/bcm_kona_timer.c

0 → 100644
+211 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2012 Broadcom Corporation

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation version 2.

 *

 * This program is distributed "as is" WITHOUT ANY WARRANTY of any

 * kind, whether express or implied; without even the implied warranty

 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */



#include <linux/init.h>

#include <linux/irq.h>

#include <linux/interrupt.h>

#include <linux/jiffies.h>

#include <linux/clockchips.h>

#include <linux/types.h>



#include <linux/io.h>

#include <asm/mach/time.h>



#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/of_irq.h>





#define KONA_GPTIMER_STCS_OFFSET			0x00000000

#define KONA_GPTIMER_STCLO_OFFSET			0x00000004

#define KONA_GPTIMER_STCHI_OFFSET			0x00000008

#define KONA_GPTIMER_STCM0_OFFSET			0x0000000C



#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT		0

#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT		4



struct kona_bcm_timers {

	int tmr_irq;

	void __iomem *tmr_regs;

};



static struct kona_bcm_timers timers;



static u32 arch_timer_rate;



/*

 * We use the peripheral timers for system tick, the cpu global timer for

 * profile tick

 */

static void kona_timer_disable_and_clear(void __iomem *base)

{

	uint32_t reg;



	/*

	 * clear and disable interrupts

	 * We are using compare/match register 0 for our system interrupts

	 */

	reg = readl(base + KONA_GPTIMER_STCS_OFFSET);



	/* Clear compare (0) interrupt */

	reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;

	/* disable compare */

	reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);



	writel(reg, base + KONA_GPTIMER_STCS_OFFSET);



}



static void

kona_timer_get_counter(void *timer_base, uint32_t *msw, uint32_t *lsw)

{

	void __iomem *base = IOMEM(timer_base);

	int loop_limit = 4;



	/*

	 * Read 64-bit free running counter

	 * 1. Read hi-word

	 * 2. Read low-word

	 * 3. Read hi-word again

	 * 4.1

	 *      if new hi-word is not equal to previously read hi-word, then

	 *      start from #1

	 * 4.2

	 *      if new hi-word is equal to previously read hi-word then stop.

	 */



	while (--loop_limit) {

		*msw = readl(base + KONA_GPTIMER_STCHI_OFFSET);

		*lsw = readl(base + KONA_GPTIMER_STCLO_OFFSET);

		if (*msw == readl(base + KONA_GPTIMER_STCHI_OFFSET))

			break;

	}

	if (!loop_limit) {

		pr_err("bcm_kona_timer: getting counter failed.\n");

		pr_err(" Timer will be impacted\n");

	}



	return;

}



static const struct of_device_id bcm_timer_ids[] __initconst = {

	{.compatible = "bcm,kona-timer"},

	{},

};



static void __init kona_timers_init(void)

{

	struct device_node *node;

	u32 freq;



	node = of_find_matching_node(NULL, bcm_timer_ids);



	if (!node)

		panic("No timer");



	if (!of_property_read_u32(node, "clock-frequency", &freq))

		arch_timer_rate = freq;

	else

		panic("clock-frequency not set in the .dts file");



	/* Setup IRQ numbers */

	timers.tmr_irq = irq_of_parse_and_map(node, 0);



	/* Setup IO addresses */

	timers.tmr_regs = of_iomap(node, 0);



	kona_timer_disable_and_clear(timers.tmr_regs);

}



static int kona_timer_set_next_event(unsigned long clc,

				  struct clock_event_device *unused)

{

	/*

	 * timer (0) is disabled by the timer interrupt already

	 * so, here we reload the next event value and re-enable

	 * the timer.

	 *

	 * This way, we are potentially losing the time between

	 * timer-interrupt->set_next_event. CPU local timers, when

	 * they come in should get rid of skew.

	 */



	uint32_t lsw, msw;

	uint32_t reg;



	kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);



	/* Load the "next" event tick value */

	writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);



	/* Enable compare */

	reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);

	reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);

	writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);



	return 0;

}



static void kona_timer_set_mode(enum clock_event_mode mode,

			     struct clock_event_device *unused)

{

	switch (mode) {

	case CLOCK_EVT_MODE_ONESHOT:

		/* by default mode is one shot don't do any thing */

		break;

	case CLOCK_EVT_MODE_UNUSED:

	case CLOCK_EVT_MODE_SHUTDOWN:

	default:

		kona_timer_disable_and_clear(timers.tmr_regs);

	}

}



static struct clock_event_device kona_clockevent_timer = {

	.name = "timer 1",

	.features = CLOCK_EVT_FEAT_ONESHOT,

	.set_next_event = kona_timer_set_next_event,

	.set_mode = kona_timer_set_mode

};



static void __init kona_timer_clockevents_init(void)

{

	kona_clockevent_timer.cpumask = cpumask_of(0);

	clockevents_config_and_register(&kona_clockevent_timer,

		arch_timer_rate, 6, 0xffffffff);

}



static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)

{

	struct clock_event_device *evt = &kona_clockevent_timer;



	kona_timer_disable_and_clear(timers.tmr_regs);

	evt->event_handler(evt);

	return IRQ_HANDLED;

}



static struct irqaction kona_timer_irq = {

	.name = "Kona Timer Tick",

	.flags = IRQF_TIMER,

	.handler = kona_timer_interrupt,

};



static void __init kona_timer_init(void)

{

	kona_timers_init();

	kona_timer_clockevents_init();

	setup_irq(timers.tmr_irq, &kona_timer_irq);

	kona_timer_set_next_event((arch_timer_rate / HZ), NULL);

}



CLOCKSOURCE_OF_DECLARE(bcm_kona, "bcm,kona-timer",

	kona_timer_init);

CRA Git | Maintained and supported by SUSTech CRA and CCSE