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/clk.h>
9 #include <linux/clockchips.h>
10 #include <linux/interrupt.h>
11 #include <linux/mfd/stm32-lptimer.h>
12 #include <linux/module.h>
13 #include <linux/of_address.h>
14 #include <linux/of_irq.h>
15 #include <linux/platform_device.h>
16 #include <linux/pm_wakeirq.h>
17
18 #define CFGR_PSC_OFFSET 9
19 #define STM32_LP_RATING 1000
20 #define STM32_TARGET_CLKRATE (32000 * HZ)
21 #define STM32_LP_MAX_PSC 7
22
23 struct stm32_lp_private {
24 struct regmap *reg;
25 struct clock_event_device clkevt;
26 unsigned long period;
27 struct device *dev;
28 };
29
30 static struct stm32_lp_private*
to_priv(struct clock_event_device * clkevt)31 to_priv(struct clock_event_device *clkevt)
32 {
33 return container_of(clkevt, struct stm32_lp_private, clkevt);
34 }
35
stm32_clkevent_lp_shutdown(struct clock_event_device * clkevt)36 static int stm32_clkevent_lp_shutdown(struct clock_event_device *clkevt)
37 {
38 struct stm32_lp_private *priv = to_priv(clkevt);
39
40 regmap_write(priv->reg, STM32_LPTIM_CR, 0);
41 regmap_write(priv->reg, STM32_LPTIM_IER, 0);
42 /* clear pending flags */
43 regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
44
45 return 0;
46 }
47
stm32_clkevent_lp_set_timer(unsigned long evt,struct clock_event_device * clkevt,int is_periodic)48 static int stm32_clkevent_lp_set_timer(unsigned long evt,
49 struct clock_event_device *clkevt,
50 int is_periodic)
51 {
52 struct stm32_lp_private *priv = to_priv(clkevt);
53
54 /* disable LPTIMER to be able to write into IER register*/
55 regmap_write(priv->reg, STM32_LPTIM_CR, 0);
56 /* enable ARR interrupt */
57 regmap_write(priv->reg, STM32_LPTIM_IER, STM32_LPTIM_ARRMIE);
58 /* enable LPTIMER to be able to write into ARR register */
59 regmap_write(priv->reg, STM32_LPTIM_CR, STM32_LPTIM_ENABLE);
60 /* set next event counter */
61 regmap_write(priv->reg, STM32_LPTIM_ARR, evt);
62
63 /* start counter */
64 if (is_periodic)
65 regmap_write(priv->reg, STM32_LPTIM_CR,
66 STM32_LPTIM_CNTSTRT | STM32_LPTIM_ENABLE);
67 else
68 regmap_write(priv->reg, STM32_LPTIM_CR,
69 STM32_LPTIM_SNGSTRT | STM32_LPTIM_ENABLE);
70
71 return 0;
72 }
73
stm32_clkevent_lp_set_next_event(unsigned long evt,struct clock_event_device * clkevt)74 static int stm32_clkevent_lp_set_next_event(unsigned long evt,
75 struct clock_event_device *clkevt)
76 {
77 return stm32_clkevent_lp_set_timer(evt, clkevt,
78 clockevent_state_periodic(clkevt));
79 }
80
stm32_clkevent_lp_set_periodic(struct clock_event_device * clkevt)81 static int stm32_clkevent_lp_set_periodic(struct clock_event_device *clkevt)
82 {
83 struct stm32_lp_private *priv = to_priv(clkevt);
84
85 return stm32_clkevent_lp_set_timer(priv->period, clkevt, true);
86 }
87
stm32_clkevent_lp_set_oneshot(struct clock_event_device * clkevt)88 static int stm32_clkevent_lp_set_oneshot(struct clock_event_device *clkevt)
89 {
90 struct stm32_lp_private *priv = to_priv(clkevt);
91
92 return stm32_clkevent_lp_set_timer(priv->period, clkevt, false);
93 }
94
stm32_clkevent_lp_irq_handler(int irq,void * dev_id)95 static irqreturn_t stm32_clkevent_lp_irq_handler(int irq, void *dev_id)
96 {
97 struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
98 struct stm32_lp_private *priv = to_priv(clkevt);
99
100 regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
101
102 if (clkevt->event_handler)
103 clkevt->event_handler(clkevt);
104
105 return IRQ_HANDLED;
106 }
107
stm32_clkevent_lp_set_prescaler(struct stm32_lp_private * priv,unsigned long * rate)108 static void stm32_clkevent_lp_set_prescaler(struct stm32_lp_private *priv,
109 unsigned long *rate)
110 {
111 int i;
112
113 for (i = 0; i <= STM32_LP_MAX_PSC; i++) {
114 if (DIV_ROUND_CLOSEST(*rate, 1 << i) < STM32_TARGET_CLKRATE)
115 break;
116 }
117
118 regmap_write(priv->reg, STM32_LPTIM_CFGR, i << CFGR_PSC_OFFSET);
119
120 /* Adjust rate and period given the prescaler value */
121 *rate = DIV_ROUND_CLOSEST(*rate, (1 << i));
122 priv->period = DIV_ROUND_UP(*rate, HZ);
123 }
124
stm32_clkevent_lp_init(struct stm32_lp_private * priv,struct device_node * np,unsigned long rate)125 static void stm32_clkevent_lp_init(struct stm32_lp_private *priv,
126 struct device_node *np, unsigned long rate)
127 {
128 priv->clkevt.name = np->full_name;
129 priv->clkevt.cpumask = cpu_possible_mask;
130 priv->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
131 CLOCK_EVT_FEAT_ONESHOT;
132 priv->clkevt.set_state_shutdown = stm32_clkevent_lp_shutdown;
133 priv->clkevt.set_state_periodic = stm32_clkevent_lp_set_periodic;
134 priv->clkevt.set_state_oneshot = stm32_clkevent_lp_set_oneshot;
135 priv->clkevt.set_next_event = stm32_clkevent_lp_set_next_event;
136 priv->clkevt.rating = STM32_LP_RATING;
137
138 clockevents_config_and_register(&priv->clkevt, rate, 0x1,
139 STM32_LPTIM_MAX_ARR);
140 }
141
stm32_clkevent_lp_probe(struct platform_device * pdev)142 static int stm32_clkevent_lp_probe(struct platform_device *pdev)
143 {
144 struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
145 struct stm32_lp_private *priv;
146 unsigned long rate;
147 int ret, irq;
148
149 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
150 if (!priv)
151 return -ENOMEM;
152
153 priv->reg = ddata->regmap;
154 ret = clk_prepare_enable(ddata->clk);
155 if (ret)
156 return -EINVAL;
157
158 rate = clk_get_rate(ddata->clk);
159 if (!rate) {
160 ret = -EINVAL;
161 goto out_clk_disable;
162 }
163
164 irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0);
165 if (irq <= 0) {
166 ret = irq;
167 goto out_clk_disable;
168 }
169
170 if (of_property_read_bool(pdev->dev.parent->of_node, "wakeup-source")) {
171 ret = device_init_wakeup(&pdev->dev, true);
172 if (ret)
173 goto out_clk_disable;
174
175 ret = dev_pm_set_wake_irq(&pdev->dev, irq);
176 if (ret)
177 goto out_clk_disable;
178 }
179
180 ret = devm_request_irq(&pdev->dev, irq, stm32_clkevent_lp_irq_handler,
181 IRQF_TIMER, pdev->name, &priv->clkevt);
182 if (ret)
183 goto out_clk_disable;
184
185 stm32_clkevent_lp_set_prescaler(priv, &rate);
186
187 stm32_clkevent_lp_init(priv, pdev->dev.parent->of_node, rate);
188
189 priv->dev = &pdev->dev;
190
191 return 0;
192
193 out_clk_disable:
194 clk_disable_unprepare(ddata->clk);
195 return ret;
196 }
197
stm32_clkevent_lp_remove(struct platform_device * pdev)198 static int stm32_clkevent_lp_remove(struct platform_device *pdev)
199 {
200 return -EBUSY; /* cannot unregister clockevent */
201 }
202
203 static const struct of_device_id stm32_clkevent_lp_of_match[] = {
204 { .compatible = "st,stm32-lptimer-timer", },
205 {},
206 };
207 MODULE_DEVICE_TABLE(of, stm32_clkevent_lp_of_match);
208
209 static struct platform_driver stm32_clkevent_lp_driver = {
210 .probe = stm32_clkevent_lp_probe,
211 .remove = stm32_clkevent_lp_remove,
212 .driver = {
213 .name = "stm32-lptimer-timer",
214 .of_match_table = of_match_ptr(stm32_clkevent_lp_of_match),
215 },
216 };
217 module_platform_driver(stm32_clkevent_lp_driver);
218
219 MODULE_ALIAS("platform:stm32-lptimer-timer");
220 MODULE_DESCRIPTION("STMicroelectronics STM32 clockevent low power driver");
221 MODULE_LICENSE("GPL v2");
222