clocksource: Provide timekeeping for efm32 SoCs

An efm32 features 4 16-bit timers with a 10-bit prescaler. This driver
provides clocksource and clock event device using one timer instance
each.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

1 files changed, 275 insertions, 0 deletions

diff --git a/drivers/clocksource/time-efm32.c b/drivers/clocksource/time-efm32.c
new file mode 100644
index 000000000000..1a6205b7bed3
--- /dev/null
+++ b/drivers/clocksource/time-efm32.c
@@ -0,0 +1,275 @@
+/*
+ * Copyright (C) 2013 Pengutronix
+ * Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.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                        0x00000001
+#define TIMERn_CMD_STOP                         0x00000002
+
+#define TIMERn_IEN                      0x0c
+#define TIMERn_IF                       0x10
+#define TIMERn_IFS                      0x14
+#define TIMERn_IFC                      0x18
+#define TIMERn_IRQ_UF                           0x00000002
+
+#define TIMERn_TOP                      0x1c
+#define TIMERn_CNT                      0x24
+
+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 __init 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;
+}
+
+/*
+ * This function asserts that we have exactly one clocksource and one
+ * clock_event_device in the end.
+ */
+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);