[PATCH V6] ARM: bcm281xx: Add timer driver
Christian Daudt
csd at broadcom.com
Tue Feb 26 12:16:55 EST 2013
This adds support for the Broadcom timer, used in the following SoCs:
BCM11130, BCM11140, BCM11351, BCM28145, BCM28155
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 at broadcom.com>
Acked-by: Arnd Bergmann <arnd at arndb.de>
Acked-by: John Stultz <johnstul at us.ibm.com>
Reviewed-by: Stephen Warren <swarren at nvidia.com>
diff --git a/Documentation/devicetree/bindings/arm/bcm/bcm,kona-timer.txt b/Documentation/devicetree/bindings/arm/bcm/bcm,kona-timer.txt
new file mode 100644
index 0000000..59fa6e6
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/bcm/bcm,kona-timer.txt
@@ -0,0 +1,19 @@
+Broadcom Kona Family timer
+-----------------------------------------------------
+This timer is used in the following Broadcom SoCs:
+ BCM11130, BCM11140, BCM11351, BCM28145, BCM28155
+
+Required properties:
+- compatible : "bcm,kona-timer"
+- reg : Register range for the timer
+- interrupts : interrupt for the timer
+- clock-frequency: frequency that the clock operates
+
+Example:
+ timer at 35006000 {
+ compatible = "bcm,kona-timer";
+ reg = <0x35006000 0x1000>;
+ interrupts = <0x0 7 0x4>;
+ clock-frequency = <32768>;
+ };
+
diff --git a/arch/arm/boot/dts/bcm11351.dtsi b/arch/arm/boot/dts/bcm11351.dtsi
index ad13588..8f71f40 100644
--- a/arch/arm/boot/dts/bcm11351.dtsi
+++ b/arch/arm/boot/dts/bcm11351.dtsi
@@ -47,4 +47,12 @@
cache-unified;
cache-level = <2>;
};
+
+ timer at 35006000 {
+ compatible = "bcm,kona-timer";
+ reg = <0x35006000 0x1000>;
+ interrupts = <0x0 7 0x4>;
+ clock-frequency = <32768>;
+ };
+
};
diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
index bf02471..f112895 100644
--- a/arch/arm/mach-bcm/Kconfig
+++ b/arch/arm/mach-bcm/Kconfig
@@ -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
diff --git a/arch/arm/mach-bcm/board_bcm.c b/arch/arm/mach-bcm/board_bcm.c
index f0f9aba..2595935 100644
--- a/arch/arm/mach-bcm/board_bcm.c
+++ b/arch/arm/mach-bcm/board_bcm.c
@@ -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
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 7d671b8..5b4a33a 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -19,5 +19,6 @@ 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
diff --git a/drivers/clocksource/bcm_kona_timer.c b/drivers/clocksource/bcm_kona_timer.c
new file mode 100644
index 0000000..350f493
--- /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);
--
1.7.1
More information about the linux-arm-kernel
mailing list