Re: [RFC PATCH 02/10] clockevents/drivers: add MPS2 Timer driver
From: Daniel Lezcano
Date: Wed Nov 25 2015 - 08:40:18 EST
On 11/25/2015 11:33 AM, Vladimir Murzin wrote:
MPS2 platform has simple 32 bits general purpose countdown timers.
The driver uses the first detected timer as a clocksource and the rest
of the timers as a clockevent
Signed-off-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>
---
drivers/clocksource/Kconfig | 5 +
drivers/clocksource/Makefile | 1 +
drivers/clocksource/mps2-timer.c | 280 ++++++++++++++++++++++++++++++++++++++
3 files changed, 286 insertions(+)
create mode 100644 drivers/clocksource/mps2-timer.c
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 71cfdf7..552ab54 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -136,6 +136,11 @@ config CLKSRC_STM32
depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)
select CLKSRC_MMIO
+config CLKSRC_MPS2
+ bool "Clocksource for MPS2 SoCs"
+ depends on OF && (ARM || COMPILE_TEST)
bool "Clocksource for MPS2 SoCs" if COMPILE_TEST
depends on OF && ARM
+ select CLKSRC_MMIO
+
config ARM_ARCH_TIMER
bool
select CLKSRC_OF if OF
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 56bd16e..7033b9c 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_CLKSRC_EFM32) += time-efm32.o
obj-$(CONFIG_CLKSRC_STM32) += timer-stm32.o
obj-$(CONFIG_CLKSRC_EXYNOS_MCT) += exynos_mct.o
obj-$(CONFIG_CLKSRC_LPC32XX) += time-lpc32xx.o
+obj-$(CONFIG_CLKSRC_MPS2) += mps2-timer.o
obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o
obj-$(CONFIG_FSL_FTM_TIMER) += fsl_ftm_timer.o
obj-$(CONFIG_VF_PIT_TIMER) += vf_pit_timer.o
diff --git a/drivers/clocksource/mps2-timer.c b/drivers/clocksource/mps2-timer.c
new file mode 100644
index 0000000..77befe2
--- /dev/null
+++ b/drivers/clocksource/mps2-timer.c
@@ -0,0 +1,280 @@
+/*
+ * Copyright (C) 2015 ARM Limited
+ *
+ * Author: Vladimir Murzin <vladimir.murzin@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#define TIMER_CTRL 0x0
+#define TIMER_CTRL_ENABLE BIT(0)
+#define TIMER_CTRL_IE BIT(3)
+
+#define TIMER_VALUE 0x4
+#define TIMER_RELOAD 0x8
+#define TIMER_INT 0xc
+
+struct clockevent_mps2 {
+ void __iomem *reg;
+ u32 clock_count_per_tick;
+ struct clock_event_device clkevt;
+};
+
+static void __iomem *sched_clock_base;
+
+static u64 notrace mps2_sched_read(void)
+{
+ return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
+}
+
+
extra line.
+static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
+{
+ return container_of(c, struct clockevent_mps2, clkevt);
+}
+
+static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
+{
+ writel(val, to_mps2_clkevt(c)->reg + offset);
+}
+
+static int mps2_timer_shutdown(struct clock_event_device *ce)
+{
+ clockevent_mps2_writel(0, ce, TIMER_RELOAD);
+ clockevent_mps2_writel(0, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
+{
+ clockevent_mps2_writel(next, ce, TIMER_VALUE);
+ clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static int mps2_timer_set_periodic(struct clock_event_device *ce)
+{
+ u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
+
+ clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
+ clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
+ clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
+{
+ struct clockevent_mps2 *ce = dev_id;
+ u32 status = readl(ce->reg + TIMER_INT);
+
+ if (!status)
+ return IRQ_NONE;
Why that could happen ? Add a comment.
+
+ writel(1, ce->reg + TIMER_INT);
+
+ ce->clkevt.event_handler(&ce->clkevt);
+
+ return IRQ_HANDLED;
+}
+
+static int __init mps2_clockevents_init(struct device_node *np)
+{
+ void __iomem *base;
+ struct clk *clk;
+ struct irqaction *ia;
+ struct clockevent_mps2 *ce;
+ u32 rate;
+ int irq, ret;
+ const char *name = "mps2-clkevt";
+
+ ret = of_property_read_u32(np, "clock-frequency", &rate);
+
extra line.
+ if (ret) {
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ ret = PTR_ERR(clk);
+ pr_err("failed to get clock for clockevent: %d\n", ret);
+ goto err_clk_get;
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("failed to enable clock for clockevent: %d\n", ret);
+ clk_put(clk);
+ goto err_clk_enable;
+ }
+
+ rate = clk_get_rate(clk);
+ }
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map register for clockevent: %d\n", ret);
+ goto err_iomap;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ ret = -ENOENT;
+ pr_err("failed to get irq for clockevent: %d\n", ret);
+ goto err_get_irq;
+ }
+
+ ce = kzalloc(sizeof(struct clockevent_mps2), GFP_KERNEL);
+ if (!ce) {
+ ret = -ENOMEM;
+ pr_err("failed to allocate clockevent: %d\n", ret);
+ goto err_ce_alloc;
+ }
+
+ ce->reg = base;
+ ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
+ ce->clkevt.irq = irq;
+ ce->clkevt.name = name;
+ ce->clkevt.rating = 200;
+ ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ ce->clkevt.cpumask = cpu_possible_mask;
+ ce->clkevt.set_state_shutdown = mps2_timer_shutdown,
+ ce->clkevt.set_state_periodic = mps2_timer_set_periodic,
+ ce->clkevt.set_state_oneshot = mps2_timer_shutdown,
+ ce->clkevt.set_next_event = mps2_timer_set_next_event;
+
+ ia = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
+ if (!ia) {
+ ret = -ENOMEM;
+ pr_err("failed to allocate irqaction: %d\n", ret);
+ goto err_ia_alloc;
+ }
+
+ ia->name = name;
+ ia->flags = IRQF_TIMER;
+ ia->handler = mps2_timer_interrupt;
+ ia->dev_id = ce;
+
+ writel(0, base + TIMER_CTRL);
+
+ ret = setup_irq(irq, ia);
Use request_irq here, that will save some extra code in this driver.
+ if (ret) {
+ pr_err("failed to setup irq: %d\n", ret);
+ goto err_setup_irq;
+ }
+
+ clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
+
+ return 0;
+
+err_setup_irq:
+ kfree(ia);
+err_ia_alloc:
+ kfree(ce);
+err_ce_alloc:
+err_get_irq:
+ iounmap(base);
+err_iomap:
+ clk_disable_unprepare(clk);
+err_clk_enable:
+ clk_put(clk);
+err_clk_get:
+ return ret;
+}
+
+static int mps2_clocksource_init(struct device_node *np)
__init annotation.
+{
+ void __iomem *base;
+ struct clk *clk;
+ u32 rate;
+ int ret;
+ const char *name = "mps2-clksrc";
+
+ ret = of_property_read_u32(np, "clock-frequency", &rate);
+
extra line.
+ if (ret) {
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ ret = PTR_ERR(clk);
+ pr_err("failed to get clock for clocksource: %d\n", ret);
+ goto err_clk_get;
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("failed to enable clock for clocksource: %d\n", ret);
+ clk_put(clk);
+ goto err_clk_enable;
+ }
+
+ rate = clk_get_rate(clk);
+ }
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map register for clocksource: %d\n", ret);
+ goto err_iomap;
+ }
+
+ writel(0, base + TIMER_CTRL);
+
+ writel(0xffffffff, base + TIMER_VALUE);
+ writel(0xffffffff, base + TIMER_RELOAD);
+
+ writel(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
A comment would help to understand the above 4 lines.
+ ret = clocksource_mmio_init(base + TIMER_VALUE, name,
+ rate, 200, 32,
+ clocksource_mmio_readl_down);
+ if (ret) {
+ pr_err("failed to init clocksource: %d\n", ret);
+ goto err_clocksource_init;
+ }
+
+ sched_clock_base = base;
+ sched_clock_register(mps2_sched_read, 32, rate);
+
+ return 0;
+
+err_clocksource_init:
+ iounmap(base);
+err_iomap:
+ clk_disable_unprepare(clk);
+err_clk_enable:
+ clk_put(clk);
+err_clk_get:
+ return ret;
+
extra line.
+}
+
+static void __init mps2_timer_init(struct device_node *np)
+{
+ static int clksrc;
+
+ if (!clksrc && !mps2_clocksource_init(np))
+ clksrc = 1;
+ else
+ mps2_clockevents_init(np);
That assumes the clocksource is defined before the clockevents in the
DT. If it is not the case, the mps2_clocksource_init will fail (and spit
errors) and mps2_clockevents_init() won't be called.
+}
+
+CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
--
<http://www.linaro.org/> Linaro.org â Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/