2 * Copyright (C) Maxime Coquelin 2015
3 * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com>
4 * License terms: GNU General Public License (GPL), version 2
6 * Inspired by time-efm32.c from Uwe Kleine-Koenig
9 #include <linux/kernel.h>
10 #include <linux/clocksource.h>
11 #include <linux/clockchips.h>
12 #include <linux/irq.h>
13 #include <linux/interrupt.h>
15 #include <linux/of_address.h>
16 #include <linux/of_irq.h>
17 #include <linux/clk.h>
18 #include <linux/reset.h>
19 #include <linux/slab.h>
28 #define TIM_CR1_CEN BIT(0)
29 #define TIM_CR1_OPM BIT(3)
30 #define TIM_CR1_ARPE BIT(7)
32 #define TIM_DIER_UIE BIT(0)
34 #define TIM_SR_UIF BIT(0)
36 #define TIM_EGR_UG BIT(0)
38 struct stm32_clock_event_ddata {
39 struct clock_event_device evtdev;
40 unsigned periodic_top;
44 static int stm32_clock_event_shutdown(struct clock_event_device *evtdev)
46 struct stm32_clock_event_ddata *data =
47 container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
48 void *base = data->base;
50 writel_relaxed(0, base + TIM_CR1);
54 static int stm32_clock_event_set_periodic(struct clock_event_device *evtdev)
56 struct stm32_clock_event_ddata *data =
57 container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
58 void *base = data->base;
60 writel_relaxed(data->periodic_top, base + TIM_ARR);
61 writel_relaxed(TIM_CR1_ARPE | TIM_CR1_CEN, base + TIM_CR1);
65 static int stm32_clock_event_set_next_event(unsigned long evt,
66 struct clock_event_device *evtdev)
68 struct stm32_clock_event_ddata *data =
69 container_of(evtdev, struct stm32_clock_event_ddata, evtdev);
71 writel_relaxed(evt, data->base + TIM_ARR);
72 writel_relaxed(TIM_CR1_ARPE | TIM_CR1_OPM | TIM_CR1_CEN,
73 data->base + TIM_CR1);
78 static irqreturn_t stm32_clock_event_handler(int irq, void *dev_id)
80 struct stm32_clock_event_ddata *data = dev_id;
82 writel_relaxed(0, data->base + TIM_SR);
84 data->evtdev.event_handler(&data->evtdev);
89 static struct stm32_clock_event_ddata clock_event_ddata = {
91 .name = "stm32 clockevent",
92 .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
93 .set_state_shutdown = stm32_clock_event_shutdown,
94 .set_state_periodic = stm32_clock_event_set_periodic,
95 .set_state_oneshot = stm32_clock_event_shutdown,
96 .tick_resume = stm32_clock_event_shutdown,
97 .set_next_event = stm32_clock_event_set_next_event,
102 static int __init stm32_clockevent_init(struct device_node *np)
104 struct stm32_clock_event_ddata *data = &clock_event_ddata;
106 struct reset_control *rstc;
107 unsigned long rate, max_delta;
108 int irq, ret, bits, prescaler = 1;
110 data = kmemdup(&clock_event_ddata, sizeof(*data), GFP_KERNEL);
114 clk = of_clk_get(np, 0);
117 pr_err("failed to get clock for clockevent (%d)\n", ret);
121 ret = clk_prepare_enable(clk);
123 pr_err("failed to enable timer clock for clockevent (%d)\n",
128 rate = clk_get_rate(clk);
130 rstc = of_reset_control_get(np, NULL);
132 reset_control_assert(rstc);
133 reset_control_deassert(rstc);
136 data->base = of_iomap(np, 0);
139 pr_err("failed to map registers for clockevent\n");
143 irq = irq_of_parse_and_map(np, 0);
146 pr_err("%s: failed to get irq.\n", np->full_name);
150 /* Detect whether the timer is 16 or 32 bits */
151 writel_relaxed(~0U, data->base + TIM_ARR);
152 max_delta = readl_relaxed(data->base + TIM_ARR);
153 if (max_delta == ~0U) {
160 writel_relaxed(0, data->base + TIM_ARR);
162 writel_relaxed(prescaler - 1, data->base + TIM_PSC);
163 writel_relaxed(TIM_EGR_UG, data->base + TIM_EGR);
164 writel_relaxed(0, data->base + TIM_SR);
165 writel_relaxed(TIM_DIER_UIE, data->base + TIM_DIER);
167 data->periodic_top = DIV_ROUND_CLOSEST(rate, prescaler * HZ);
169 clockevents_config_and_register(&data->evtdev,
170 DIV_ROUND_CLOSEST(rate, prescaler),
173 ret = request_irq(irq, stm32_clock_event_handler, IRQF_TIMER,
174 "stm32 clockevent", data);
176 pr_err("%s: failed to request irq.\n", np->full_name);
180 pr_info("%s: STM32 clockevent driver initialized (%d bits)\n",
181 np->full_name, bits);
188 clk_disable_unprepare(clk);
196 CLOCKSOURCE_OF_DECLARE(stm32, "st,stm32-timer", stm32_clockevent_init);