--- /dev/null
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ * License terms: GNU General Public License (GPL), version 2
+ *
+ * Inspired by time-efm32.c from Uwe Kleine-Koenig
+ */
+
+#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>
+#include <linux/reset.h>
+
+#define TIM_CR1 0x00
+#define TIM_DIER 0x0c
+#define TIM_SR 0x10
+#define TIM_EGR 0x14
+#define TIM_PSC 0x28
+#define TIM_ARR 0x2c
+
+#define TIM_CR1_CEN BIT(0)
+#define TIM_CR1_OPM BIT(3)
+#define TIM_CR1_ARPE BIT(7)
+
+#define TIM_DIER_UIE BIT(0)
+
+#define TIM_SR_UIF BIT(0)
+
+#define TIM_EGR_UG BIT(0)
+
+struct stm32_clock_event_ddata {
+ struct clock_event_device evtdev;
+ unsigned periodic_top;
+ void __iomem *base;
+};
+
+static int stm32_clock_event_shutdown(struct clock_event_device *evtdev)
+{
+ struct stm32_clock_event_ddata *data =
+ container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
+ void *base = data->base;
+
+ writel_relaxed(0, base + TIM_CR1);
+ return 0;
+}
+
+static int stm32_clock_event_set_periodic(struct clock_event_device *evtdev)
+{
+ struct stm32_clock_event_ddata *data =
+ container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
+ void *base = data->base;
+
+ writel_relaxed(data->periodic_top, base + TIM_ARR);
+ writel_relaxed(TIM_CR1_ARPE | TIM_CR1_CEN, base + TIM_CR1);
+ return 0;
+}
+
+static int stm32_clock_event_set_next_event(unsigned long evt,
+ struct clock_event_device *evtdev)
+{
+ struct stm32_clock_event_ddata *data =
+ container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
+
+ writel_relaxed(evt, data->base + TIM_ARR);
+ writel_relaxed(TIM_CR1_ARPE | TIM_CR1_OPM | TIM_CR1_CEN,
+ data->base + TIM_CR1);
+
+ return 0;
+}
+
+static irqreturn_t stm32_clock_event_handler(int irq, void *dev_id)
+{
+ struct stm32_clock_event_ddata *data = dev_id;
+
+ writel_relaxed(0, data->base + TIM_SR);
+
+ data->evtdev.event_handler(&data->evtdev);
+
+ return IRQ_HANDLED;
+}
+
+static struct stm32_clock_event_ddata clock_event_ddata = {
+ .evtdev = {
+ .name = "stm32 clockevent",
+ .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
+ .set_state_shutdown = stm32_clock_event_shutdown,
+ .set_state_periodic = stm32_clock_event_set_periodic,
+ .set_state_oneshot = stm32_clock_event_shutdown,
+ .tick_resume = stm32_clock_event_shutdown,
+ .set_next_event = stm32_clock_event_set_next_event,
+ .rating = 200,
+ },
+};
+
+static void __init stm32_clockevent_init(struct device_node *np)
+{
+ struct stm32_clock_event_ddata *data = &clock_event_ddata;
+ struct clk *clk;
+ struct reset_control *rstc;
+ unsigned long rate, max_delta;
+ int irq, ret, bits, prescaler = 1;
+
+ 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);
+
+ rstc = of_reset_control_get(np, NULL);
+ if (!IS_ERR(rstc)) {
+ reset_control_assert(rstc);
+ reset_control_deassert(rstc);
+ }
+
+ data->base = of_iomap(np, 0);
+ if (!data->base) {
+ pr_err("failed to map registers for clockevent\n");
+ goto err_iomap;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ pr_err("%s: failed to get irq.\n", np->full_name);
+ goto err_get_irq;
+ }
+
+ /* Detect whether the timer is 16 or 32 bits */
+ writel_relaxed(~0U, data->base + TIM_ARR);
+ max_delta = readl_relaxed(data->base + TIM_ARR);
+ if (max_delta == ~0U) {
+ prescaler = 1;
+ bits = 32;
+ } else {
+ prescaler = 1024;
+ bits = 16;
+ }
+ writel_relaxed(0, data->base + TIM_ARR);
+
+ writel_relaxed(prescaler - 1, data->base + TIM_PSC);
+ writel_relaxed(TIM_EGR_UG, data->base + TIM_EGR);
+ writel_relaxed(TIM_DIER_UIE, data->base + TIM_DIER);
+ writel_relaxed(0, data->base + TIM_SR);
+
+ data->periodic_top = DIV_ROUND_CLOSEST(rate, prescaler * HZ);
+
+ clockevents_config_and_register(&data->evtdev,
+ DIV_ROUND_CLOSEST(rate, prescaler),
+ 0x1, max_delta);
+
+ ret = request_irq(irq, stm32_clock_event_handler, IRQF_TIMER,
+ "stm32 clockevent", data);
+ if (ret) {
+ pr_err("%s: failed to request irq.\n", np->full_name);
+ goto err_get_irq;
+ }
+
+ pr_info("%s: STM32 clockevent driver initialized (%d bits)\n",
+ np->full_name, bits);
+
+ return;
+
+err_get_irq:
+ iounmap(data->base);
+err_iomap:
+ clk_disable_unprepare(clk);
+err_clk_enable:
+ clk_put(clk);
+err_clk_get:
+ return;
+}
+
+CLOCKSOURCE_OF_DECLARE(stm32, "st,stm32-timer", stm32_clockevent_init);
Code Review / kvmfornfv.git / blobdiff