ARM: bcm281xx: Add timer driver

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

This patch needs the arm-soc/soc/next branch

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 <[email protected]>

Acked-by Arnd Bergmann <[email protected]>

Documentation/devicetree/bindings/arm/bcm/bcm,kona-timer.txt new file +19 -0

new file mode 100644
index 0000000..59fa6e6
@@ -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>;
+       };
+

arch/arm/boot/dts/bcm11351.dtsi +8 -0

index ad13588..8f71f40 100644
@@ -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>;
+       };
+
 };

arch/arm/mach-bcm/board_bcm.c +2 -4

index 3a62f1b..2457010 100644
@@ -27,12 +27,10 @@ static const struct of_device_id irq_match[] = {
        {}
 };
 
-static void timer_init(void)
-{
-}
+extern void bcm_timer_init(void);
 
 static struct sys_timer timer = {
-       .init = timer_init,
+       .init = bcm_timer_init,
 };
 
 static void __init init_irq(void)

drivers/clocksource/Makefile +1 -0

index 603be36..885afc5 100644
@@ -14,5 +14,6 @@ obj-$(CONFIG_DW_APB_TIMER_OF) += dw_apb_timer_of.o
 obj-$(CONFIG_CLKSRC_DBX500_PRCMU)      += clksrc-dbx500-prcmu.o
 obj-$(CONFIG_ARMADA_370_XP_TIMER)      += time-armada-370-xp.o
 obj-$(CONFIG_ARCH_BCM2835)     += bcm2835_timer.o
+obj-$(CONFIG_ARCH_BCM)         += bcm_kona_timer.o
 
 obj-$(CONFIG_CLKSRC_ARM_GENERIC)       += arm_generic.o

drivers/clocksource/bcm_kona_timer.c new file +206 -1

new file mode 100644
index 0000000..dbc54c2
@@ -0,0 +1,206 @@
+/*
+ * 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 bcm_timers {
+       int tmr_irq;
+       void __iomem *tmr_regs;
+};
+
+static struct 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 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
+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 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);
+
+       timer_disable_and_clear(timers.tmr_regs);
+}
+
+static int 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;
+
+       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 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:
+               timer_disable_and_clear(timers.tmr_regs);
+       }
+}
+
+static struct clock_event_device clockevent_timer = {
+       .name = "timer 1",
+       .features = CLOCK_EVT_FEAT_ONESHOT,
+       .set_next_event = timer_set_next_event,
+       .set_mode = timer_set_mode
+};
+
+static void __init timer_clockevents_init(void)
+{
+       clockevent_timer.cpumask = cpumask_of(0);
+       clockevents_config_and_register(&clockevent_timer,
+               arch_timer_rate, 6, 0xffffffff);
+}
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+       struct clock_event_device *evt = &clockevent_timer;
+
+       timer_disable_and_clear(timers.tmr_regs);
+       evt->event_handler(evt);
+       return IRQ_HANDLED;
+}
+
+static struct irqaction timer_irq = {
+       .name = "Kona Timer Tick",
+       .flags = IRQF_TIMER,
+       .handler = timer_interrupt,
+};
+
+void __init bcm_timer_init(void)
+{
+       timers_init();
+       timer_clockevents_init();
+       setup_irq(timers.tmr_irq, &timer_irq);
+       timer_set_next_event((arch_timer_rate / HZ), NULL);
+}
--

1.7.1

John,

Quoted 3 lines · Christian Daudt

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

Quoted 2 lines

This patch needs the arm-soc/soc/next branch

Given the dependencies on the new platform here, should we just merge this through arm-soc? If so, an Acked-by would be appreciated.

Alternatively, we can merge the driver and the device tree updates separately if that's easier.

Quoted 13 lines

drivers/clocksource/bcm_kona_timer.c new file +6 -0

new file mode 100644
index 0000000..dbc54c2
 
+static void __init timers_init(void)
+static int timer_set_next_event(unsigned long clc,
+                                 struct clock_event_device *unused)
+static void timer_set_mode(enum clock_event_mode mode,
+                            struct clock_event_device *unused)
+static void __init timer_clockevents_init(void)

Quoted 2 lines

+static irqreturn_t timer_interrupt(int irq, void *dev_id)

But since you pulled me in here, I've got a bike-shedding nit below (Sorry!).

Quoted 14 lines

Quoted 14 lines

drivers/clocksource/bcm_kona_timer.c new file +6 -0

new file mode 100644
index 0000000..dbc54c2
 
+static void __init timers_init(void)
+static int timer_set_next_event(unsigned long clc,
+                                 struct clock_event_device *unused)
+static void timer_set_mode(enum clock_event_mode mode,
+                            struct clock_event_device *unused)
+static void __init timer_clockevents_init(void)

Quoted 2 lines

Quoted 2 lines

+static irqreturn_t timer_interrupt(int irq, void *dev_id)

These are all terribly generic function names. I know they're static (and plenty of other driver do the same thing), but it makes grepping
for similar code a pain and can cause confusing backtraces. Maybe
consider using the kona_timer_... prefix?

Other then that, for what its worth,

Acked-by John Stultz <[email protected]>

thanks
-john