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Message-Id: <1379324644-20934-1-git-send-email-u.kleine-koenig@pengutronix.de>
Date: Mon, 16 Sep 2013 11:44:04 +0200
From: Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
kernel@...gutronix.de
Subject: [RFC, PATCH] clocksource: provide timekeeping for efm32 SoCs
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
Hello,
I'm not sure that the way I implemented if a given timer is used as
clock_source or clock_event_device is robust. Does it need locking?
The reason to create a timer device for each timer instead of a single
device of all of them is that it makes it cleaner to specify irqs and
clks which each timer has one of each respectively. I didn't find an
example, but while looking I wondered if in zevio-timer.c a single timer
can really support both clock_event and clocksource.
I guess for inclusion I need to write a document describing the
of-binding. I will include that in the next iteration.
checkpatch wails that the description of CLKSRC_EFM32 is too short. I
think it's OK though.
Best regards
Uwe
drivers/clocksource/Kconfig | 8 ++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/time-efm32.c | 274 +++++++++++++++++++++++++++++++++++++++
3 files changed, 283 insertions(+)
create mode 100644 drivers/clocksource/time-efm32.c
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 41c6946..410b152 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -70,6 +70,14 @@ config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
help
Use the always on PRCMU Timer as sched_clock
+config CLKSRC_EFM32
+ bool "Clocksource for Energy Micro's EFM32 SoCs" if !ARCH_EFM32
+ depends on OF && ARM && (ARCH_EFM32 || COMPILE_TEST)
+ default ARCH_EFM32
+ help
+ Support to use the timers of EFM32 SoCs as clock source and clock
+ event device.
+
config ARM_ARCH_TIMER
bool
select CLKSRC_OF if OF
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 704d6d3..33621ef 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_VT8500_TIMER) += vt8500_timer.o
obj-$(CONFIG_ARCH_NSPIRE) += zevio-timer.o
obj-$(CONFIG_ARCH_BCM) += bcm_kona_timer.o
obj-$(CONFIG_CADENCE_TTC_TIMER) += cadence_ttc_timer.o
+obj-$(CONFIG_CLKSRC_EFM32) += time-efm32.o
obj-$(CONFIG_CLKSRC_EXYNOS_MCT) += exynos_mct.o
obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o
obj-$(CONFIG_VF_PIT_TIMER) += vf_pit_timer.o
diff --git a/drivers/clocksource/time-efm32.c b/drivers/clocksource/time-efm32.c
new file mode 100644
index 0000000..6ead8d7
--- /dev/null
+++ b/drivers/clocksource/time-efm32.c
@@ -0,0 +1,274 @@
+/*
+ * Copyright (C) 2013 Pengutronix
+ * Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>
+ *
+ * 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/kernel.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+
+#define TIMERn_CTRL 0x00
+#define TIMERn_CTRL_PRESC(val) (((val) & 0xf) << 24)
+#define TIMERn_CTRL_PRESC_1024 TIMERn_CTRL_PRESC(10)
+#define TIMERn_CTRL_CLKSEL(val) (((val) & 0x3) << 16)
+#define TIMERn_CTRL_CLKSEL_PRESCHFPERCLK TIMERn_CTRL_CLKSEL(0)
+#define TIMERn_CTRL_OSMEN 0x00000010
+#define TIMERn_CTRL_MODE(val) (((val) & 0x3) << 0)
+#define TIMERn_CTRL_MODE_UP TIMERn_CTRL_MODE(0)
+#define TIMERn_CTRL_MODE_DOWN TIMERn_CTRL_MODE(1)
+
+#define TIMERn_CMD 0x04
+#define TIMERn_CMD_START 0x1
+#define TIMERn_CMD_STOP 0x2
+
+#define TIMERn_IEN 0x0c
+#define TIMERn_IF 0x10
+#define TIMERn_IFS 0x14
+#define TIMERn_IFC 0x18
+#define TIMERn_IRQ_UF 0x2
+#define TIMERn_IRQ_OF 0x1
+
+#define TIMERn_TOP 0x1c
+#define TIMERn_CNT 0x24
+
+#define TIMER_CLOCKSOURCE 0
+#define TIMER_CLOCKEVENT 1
+
+struct efm32_clock_event_ddata {
+ struct clock_event_device evtdev;
+ void __iomem *base;
+ unsigned periodic_top;
+};
+
+static void efm32_clock_event_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evtdev)
+{
+ struct efm32_clock_event_ddata *ddata =
+ container_of(evtdev, struct efm32_clock_event_ddata, evtdev);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ writel_relaxed(TIMERn_CMD_STOP, ddata->base + TIMERn_CMD);
+ writel_relaxed(ddata->periodic_top, ddata->base + TIMERn_TOP);
+ writel_relaxed(TIMERn_CTRL_PRESC_1024 |
+ TIMERn_CTRL_CLKSEL_PRESCHFPERCLK |
+ TIMERn_CTRL_MODE_DOWN,
+ ddata->base + TIMERn_CTRL);
+ writel_relaxed(TIMERn_CMD_START, ddata->base + TIMERn_CMD);
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ writel_relaxed(TIMERn_CMD_STOP, ddata->base + TIMERn_CMD);
+ writel_relaxed(TIMERn_CTRL_PRESC_1024 |
+ TIMERn_CTRL_CLKSEL_PRESCHFPERCLK |
+ TIMERn_CTRL_OSMEN |
+ TIMERn_CTRL_MODE_DOWN,
+ ddata->base + TIMERn_CTRL);
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ writel_relaxed(TIMERn_CMD_STOP, ddata->base + TIMERn_CMD);
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+ }
+}
+
+static int efm32_clock_event_set_next_event(unsigned long evt,
+ struct clock_event_device *evtdev)
+{
+ struct efm32_clock_event_ddata *ddata =
+ container_of(evtdev, struct efm32_clock_event_ddata, evtdev);
+
+ writel_relaxed(TIMERn_CMD_STOP, ddata->base + TIMERn_CMD);
+ writel_relaxed(evt, ddata->base + TIMERn_CNT);
+ writel_relaxed(TIMERn_CMD_START, ddata->base + TIMERn_CMD);
+
+ return 0;
+}
+
+static irqreturn_t efm32_clock_event_handler(int irq, void *dev_id)
+{
+ struct efm32_clock_event_ddata *ddata = dev_id;
+
+ writel_relaxed(TIMERn_IRQ_UF, ddata->base + TIMERn_IFC);
+
+ ddata->evtdev.event_handler(&ddata->evtdev);
+
+ return IRQ_HANDLED;
+}
+
+static struct efm32_clock_event_ddata clock_event_ddata = {
+ .evtdev = {
+ .name = "efm32 clockevent",
+ .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_MODE_PERIODIC,
+ .set_mode = efm32_clock_event_set_mode,
+ .set_next_event = efm32_clock_event_set_next_event,
+ .rating = 200,
+ },
+};
+
+static struct irqaction efm32_clock_event_irq = {
+ .name = "efm32 clockevent",
+ .flags = IRQF_TIMER,
+ .handler = efm32_clock_event_handler,
+ .dev_id = &clock_event_ddata,
+};
+
+static int efm32_clocksource_init(struct device_node *np)
+{
+ struct clk *clk;
+ void __iomem *base;
+ unsigned long rate;
+ int 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 timer clock for clocksource (%d)\n",
+ ret);
+ goto err_clk_enable;
+ }
+ rate = clk_get_rate(clk);
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map registers for clocksource\n");
+ goto err_iomap;
+ }
+
+ writel_relaxed(TIMERn_CTRL_PRESC_1024 |
+ TIMERn_CTRL_CLKSEL_PRESCHFPERCLK |
+ TIMERn_CTRL_MODE_UP, base + TIMERn_CTRL);
+ writel_relaxed(TIMERn_CMD_START, base + TIMERn_CMD);
+
+ ret = clocksource_mmio_init(base + TIMERn_CNT, "efm32 timer",
+ DIV_ROUND_CLOSEST(rate, 1024), 200, 16,
+ clocksource_mmio_readl_up);
+ if (ret) {
+ pr_err("failed to init clocksource (%d)\n", ret);
+ goto err_clocksource_init;
+ }
+
+ return 0;
+
+err_clocksource_init:
+
+ iounmap(base);
+err_iomap:
+
+ clk_disable_unprepare(clk);
+err_clk_enable:
+
+ clk_put(clk);
+err_clk_get:
+
+ return ret;
+}
+
+static int __init efm32_clockevent_init(struct device_node *np)
+{
+ struct clk *clk;
+ void __iomem *base;
+ unsigned long rate;
+ int irq;
+ int 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 timer clock for clockevent (%d)\n",
+ ret);
+ goto err_clk_enable;
+ }
+ rate = clk_get_rate(clk);
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map registers for clockevent\n");
+ goto err_iomap;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ ret = -ENOENT;
+ pr_err("failed to get irq for clockevent\n");
+ goto err_get_irq;
+ }
+
+ writel_relaxed(TIMERn_IRQ_UF, base + TIMERn_IEN);
+
+ clock_event_ddata.base = base;
+ clock_event_ddata.periodic_top = DIV_ROUND_CLOSEST(rate, 1024 * HZ);
+
+ setup_irq(irq, &efm32_clock_event_irq);
+
+ clockevents_config_and_register(&clock_event_ddata.evtdev,
+ DIV_ROUND_CLOSEST(rate, 1024), 0xf, 0xffff);
+
+ return 0;
+
+err_get_irq:
+
+ iounmap(base);
+err_iomap:
+
+ clk_disable_unprepare(clk);
+err_clk_enable:
+
+ clk_put(clk);
+err_clk_get:
+
+ return ret;
+}
+
+static void __init efm32_timer_init(struct device_node *np)
+{
+ static int has_clocksource, has_clockevent;
+ int ret;
+
+ if (!has_clocksource) {
+ ret = efm32_clocksource_init(np);
+ if (!ret) {
+ has_clocksource = 1;
+ return;
+ }
+ }
+
+ if (!has_clockevent) {
+ ret = efm32_clockevent_init(np);
+ if (!ret) {
+ has_clockevent = 1;
+ return;
+ }
+ }
+}
+CLOCKSOURCE_OF_DECLARE(efm32, "efm32,timer", efm32_timer_init);
--
1.8.4.rc3
--
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