1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) STMicroelectronics 2019 - All Rights Reserved
4 * Authors: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
5 * Pascal Paillet <p.paillet@st.com> for STMicroelectronics.
6 */
7
8#include <linux/bitfield.h>
9#include <linux/clk.h>
10#include <linux/clockchips.h>
11#include <linux/interrupt.h>
12#include <linux/mfd/stm32-lptimer.h>
13#include <linux/module.h>
14#include <linux/of_address.h>
15#include <linux/of_irq.h>
16#include <linux/platform_device.h>
17#include <linux/pm_wakeirq.h>
18
19#define CFGR_PSC_OFFSET 9
20#define STM32_LP_RATING 1000
21#define STM32_TARGET_CLKRATE (32000 * HZ)
22#define STM32_LP_MAX_PSC 7
23
24struct stm32_lp_private {
25 struct regmap *reg;
26 struct clock_event_device clkevt;
27 unsigned long period;
28 u32 psc;
29 struct device *dev;
30 struct clk *clk;
31 u32 version;
32};
33
34static struct stm32_lp_private*
35to_priv(struct clock_event_device *clkevt)
36{
37 return container_of(clkevt, struct stm32_lp_private, clkevt);
38}
39
40static int stm32_clkevent_lp_shutdown(struct clock_event_device *clkevt)
41{
42 struct stm32_lp_private *priv = to_priv(clkevt);
43
44 regmap_write(map: priv->reg, STM32_LPTIM_CR, val: 0);
45 regmap_write(map: priv->reg, STM32_LPTIM_IER, val: 0);
46 /* clear pending flags */
47 regmap_write(map: priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
48
49 return 0;
50}
51
52static int stm32mp25_clkevent_lp_set_evt(struct stm32_lp_private *priv, unsigned long evt)
53{
54 int ret;
55 u32 val;
56
57 regmap_read(map: priv->reg, STM32_LPTIM_CR, val: &val);
58 if (!FIELD_GET(STM32_LPTIM_ENABLE, val)) {
59 /* Enable LPTIMER to be able to write into IER and ARR registers */
60 regmap_write(map: priv->reg, STM32_LPTIM_CR, STM32_LPTIM_ENABLE);
61 /*
62 * After setting the ENABLE bit, a delay of two counter clock cycles is needed
63 * before the LPTIM is actually enabled. For 32KHz rate, this makes approximately
64 * 62.5 micro-seconds, round it up.
65 */
66 udelay(usec: 63);
67 }
68 /* set next event counter */
69 regmap_write(map: priv->reg, STM32_LPTIM_ARR, val: evt);
70 /* enable ARR interrupt */
71 regmap_write(map: priv->reg, STM32_LPTIM_IER, STM32_LPTIM_ARRMIE);
72
73 /* Poll DIEROK and ARROK to ensure register access has completed */
74 ret = regmap_read_poll_timeout_atomic(priv->reg, STM32_LPTIM_ISR, val,
75 (val & STM32_LPTIM_DIEROK_ARROK) ==
76 STM32_LPTIM_DIEROK_ARROK,
77 10, 500);
78 if (ret) {
79 dev_err(priv->dev, "access to LPTIM timed out\n");
80 /* Disable LPTIMER */
81 regmap_write(map: priv->reg, STM32_LPTIM_CR, val: 0);
82 return ret;
83 }
84 /* Clear DIEROK and ARROK flags */
85 regmap_write(map: priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_DIEROKCF_ARROKCF);
86
87 return 0;
88}
89
90static void stm32_clkevent_lp_set_evt(struct stm32_lp_private *priv, unsigned long evt)
91{
92 /* disable LPTIMER to be able to write into IER register*/
93 regmap_write(map: priv->reg, STM32_LPTIM_CR, val: 0);
94 /* enable ARR interrupt */
95 regmap_write(map: priv->reg, STM32_LPTIM_IER, STM32_LPTIM_ARRMIE);
96 /* enable LPTIMER to be able to write into ARR register */
97 regmap_write(map: priv->reg, STM32_LPTIM_CR, STM32_LPTIM_ENABLE);
98 /* set next event counter */
99 regmap_write(map: priv->reg, STM32_LPTIM_ARR, val: evt);
100}
101
102static int stm32_clkevent_lp_set_timer(unsigned long evt,
103 struct clock_event_device *clkevt,
104 int is_periodic)
105{
106 struct stm32_lp_private *priv = to_priv(clkevt);
107 int ret;
108
109 if (priv->version == STM32_LPTIM_VERR_23) {
110 ret = stm32mp25_clkevent_lp_set_evt(priv, evt);
111 if (ret)
112 return ret;
113 } else {
114 stm32_clkevent_lp_set_evt(priv, evt);
115 }
116
117 /* start counter */
118 if (is_periodic)
119 regmap_write(map: priv->reg, STM32_LPTIM_CR,
120 STM32_LPTIM_CNTSTRT | STM32_LPTIM_ENABLE);
121 else
122 regmap_write(map: priv->reg, STM32_LPTIM_CR,
123 STM32_LPTIM_SNGSTRT | STM32_LPTIM_ENABLE);
124
125 return 0;
126}
127
128static int stm32_clkevent_lp_set_next_event(unsigned long evt,
129 struct clock_event_device *clkevt)
130{
131 return stm32_clkevent_lp_set_timer(evt, clkevt,
132 is_periodic: clockevent_state_periodic(dev: clkevt));
133}
134
135static int stm32_clkevent_lp_set_periodic(struct clock_event_device *clkevt)
136{
137 struct stm32_lp_private *priv = to_priv(clkevt);
138
139 return stm32_clkevent_lp_set_timer(evt: priv->period, clkevt, is_periodic: true);
140}
141
142static int stm32_clkevent_lp_set_oneshot(struct clock_event_device *clkevt)
143{
144 struct stm32_lp_private *priv = to_priv(clkevt);
145
146 return stm32_clkevent_lp_set_timer(evt: priv->period, clkevt, is_periodic: false);
147}
148
149static irqreturn_t stm32_clkevent_lp_irq_handler(int irq, void *dev_id)
150{
151 struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
152 struct stm32_lp_private *priv = to_priv(clkevt);
153
154 regmap_write(map: priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
155
156 if (clkevt->event_handler)
157 clkevt->event_handler(clkevt);
158
159 return IRQ_HANDLED;
160}
161
162static void stm32_clkevent_lp_set_prescaler(struct stm32_lp_private *priv,
163 unsigned long *rate)
164{
165 int i;
166
167 for (i = 0; i <= STM32_LP_MAX_PSC; i++) {
168 if (DIV_ROUND_CLOSEST(*rate, 1 << i) < STM32_TARGET_CLKRATE)
169 break;
170 }
171
172 regmap_write(map: priv->reg, STM32_LPTIM_CFGR, val: i << CFGR_PSC_OFFSET);
173
174 /* Adjust rate and period given the prescaler value */
175 *rate = DIV_ROUND_CLOSEST(*rate, (1 << i));
176 priv->period = DIV_ROUND_UP(*rate, HZ);
177 priv->psc = i;
178}
179
180static void stm32_clkevent_lp_suspend(struct clock_event_device *clkevt)
181{
182 struct stm32_lp_private *priv = to_priv(clkevt);
183
184 stm32_clkevent_lp_shutdown(clkevt);
185
186 /* balance clk_prepare_enable() from the probe */
187 clk_disable_unprepare(clk: priv->clk);
188}
189
190static void stm32_clkevent_lp_resume(struct clock_event_device *clkevt)
191{
192 struct stm32_lp_private *priv = to_priv(clkevt);
193
194 clk_prepare_enable(clk: priv->clk);
195
196 /* restore prescaler */
197 regmap_write(map: priv->reg, STM32_LPTIM_CFGR, val: priv->psc << CFGR_PSC_OFFSET);
198}
199
200static void stm32_clkevent_lp_init(struct stm32_lp_private *priv,
201 struct device_node *np, unsigned long rate)
202{
203 priv->clkevt.name = np->full_name;
204 priv->clkevt.cpumask = cpu_possible_mask;
205 priv->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
206 CLOCK_EVT_FEAT_ONESHOT;
207 priv->clkevt.set_state_shutdown = stm32_clkevent_lp_shutdown;
208 priv->clkevt.set_state_periodic = stm32_clkevent_lp_set_periodic;
209 priv->clkevt.set_state_oneshot = stm32_clkevent_lp_set_oneshot;
210 priv->clkevt.set_next_event = stm32_clkevent_lp_set_next_event;
211 priv->clkevt.rating = STM32_LP_RATING;
212 priv->clkevt.suspend = stm32_clkevent_lp_suspend;
213 priv->clkevt.resume = stm32_clkevent_lp_resume;
214 priv->clkevt.owner = THIS_MODULE;
215
216 clockevents_config_and_register(dev: &priv->clkevt, freq: rate, min_delta: 0x1,
217 STM32_LPTIM_MAX_ARR);
218}
219
220static int stm32_clkevent_lp_probe(struct platform_device *pdev)
221{
222 struct stm32_lptimer *ddata = dev_get_drvdata(dev: pdev->dev.parent);
223 struct stm32_lp_private *priv;
224 unsigned long rate;
225 int ret, irq;
226
227 priv = devm_kzalloc(dev: &pdev->dev, size: sizeof(*priv), GFP_KERNEL);
228 if (!priv)
229 return -ENOMEM;
230
231 priv->reg = ddata->regmap;
232 priv->version = ddata->version;
233 priv->clk = ddata->clk;
234 ret = clk_prepare_enable(clk: priv->clk);
235 if (ret)
236 return -EINVAL;
237
238 rate = clk_get_rate(clk: priv->clk);
239 if (!rate) {
240 ret = -EINVAL;
241 goto out_clk_disable;
242 }
243
244 irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0);
245 if (irq <= 0) {
246 ret = irq;
247 goto out_clk_disable;
248 }
249
250 if (of_property_read_bool(np: pdev->dev.parent->of_node, propname: "wakeup-source")) {
251 device_set_wakeup_capable(dev: &pdev->dev, capable: true);
252
253 ret = dev_pm_set_wake_irq(dev: &pdev->dev, irq);
254 if (ret)
255 goto out_clk_disable;
256 }
257
258 ret = devm_request_irq(dev: &pdev->dev, irq, handler: stm32_clkevent_lp_irq_handler,
259 IRQF_TIMER, devname: pdev->name, dev_id: &priv->clkevt);
260 if (ret)
261 goto out_clk_disable;
262
263 stm32_clkevent_lp_set_prescaler(priv, rate: &rate);
264
265 stm32_clkevent_lp_init(priv, np: pdev->dev.parent->of_node, rate);
266
267 priv->dev = &pdev->dev;
268
269 return 0;
270
271out_clk_disable:
272 clk_disable_unprepare(clk: priv->clk);
273 return ret;
274}
275
276static const struct of_device_id stm32_clkevent_lp_of_match[] = {
277 { .compatible = "st,stm32-lptimer-timer", },
278 {},
279};
280MODULE_DEVICE_TABLE(of, stm32_clkevent_lp_of_match);
281
282static struct platform_driver stm32_clkevent_lp_driver = {
283 .probe = stm32_clkevent_lp_probe,
284 .driver = {
285 .name = "stm32-lptimer-timer",
286 .of_match_table = stm32_clkevent_lp_of_match,
287 .suppress_bind_attrs = true,
288 },
289};
290module_platform_driver(stm32_clkevent_lp_driver);
291
292MODULE_DESCRIPTION("STMicroelectronics STM32 clockevent low power driver");
293

source code of linux/drivers/clocksource/timer-stm32-lp.c