diff options
author | Christian Daudt <csd@broadcom.com> | 2013-03-13 22:27:27 +0100 |
---|---|---|
committer | John Stultz <john.stultz@linaro.org> | 2013-03-28 18:58:55 +0100 |
commit | 8011657b9e63cb2e914b9a0f75233b910c1854cb (patch) | |
tree | 7eb4b207529dc5feaebf95e4335602cf64a4d887 /drivers/clocksource/bcm_kona_timer.c | |
parent | timekeeping: __timekeeping_set_tai_offset can be static (diff) | |
download | linux-8011657b9e63cb2e914b9a0f75233b910c1854cb.tar.xz linux-8011657b9e63cb2e914b9a0f75233b910c1854cb.zip |
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: Christian Daudt <csd@broadcom.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'drivers/clocksource/bcm_kona_timer.c')
-rw-r--r-- | drivers/clocksource/bcm_kona_timer.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/drivers/clocksource/bcm_kona_timer.c b/drivers/clocksource/bcm_kona_timer.c new file mode 100644 index 000000000000..350f49356458 --- /dev/null +++ b/drivers/clocksource/bcm_kona_timer.c @@ -0,0 +1,211 @@ +/* + * 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); |