diff options
Diffstat (limited to 'drivers/clocksource/timer-stm32.c')
| -rw-r--r-- | drivers/clocksource/timer-stm32.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c new file mode 100644 index 000000000000..fad2e2e7a0b8 --- /dev/null +++ b/drivers/clocksource/timer-stm32.c @@ -0,0 +1,184 @@ +/* + * 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 void stm32_clock_event_set_mode(enum clock_event_mode mode, + struct clock_event_device *evtdev) +{ + struct stm32_clock_event_ddata *data = + container_of(evtdev, struct stm32_clock_event_ddata, evtdev); + void *base = data->base; + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + writel_relaxed(data->periodic_top, base + TIM_ARR); + writel_relaxed(TIM_CR1_ARPE | TIM_CR1_CEN, base + TIM_CR1); + break; + + case CLOCK_EVT_MODE_ONESHOT: + default: + writel_relaxed(0, base + TIM_CR1); + break; + } +} + +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_mode = stm32_clock_event_set_mode, + .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(~0UL, data->base + TIM_ARR); + max_delta = readl_relaxed(data->base + TIM_ARR); + if (max_delta == ~0UL) { + 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); |