1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) STMicroelectronics 2016
4 * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
5 */
6
7 #include <linux/bitfield.h>
8 #include <linux/mfd/stm32-timers.h>
9 #include <linux/module.h>
10 #include <linux/of_platform.h>
11 #include <linux/platform_device.h>
12 #include <linux/reset.h>
13
14 #define STM32_TIMERS_MAX_REGISTERS 0x3fc
15
16 /* DIER register DMA enable bits */
17 static const u32 stm32_timers_dier_dmaen[STM32_TIMERS_MAX_DMAS] = {
18 TIM_DIER_CC1DE,
19 TIM_DIER_CC2DE,
20 TIM_DIER_CC3DE,
21 TIM_DIER_CC4DE,
22 TIM_DIER_UIE,
23 TIM_DIER_TDE,
24 TIM_DIER_COMDE
25 };
26
stm32_timers_dma_done(void * p)27 static void stm32_timers_dma_done(void *p)
28 {
29 struct stm32_timers_dma *dma = p;
30 struct dma_tx_state state;
31 enum dma_status status;
32
33 status = dmaengine_tx_status(dma->chan, dma->chan->cookie, &state);
34 if (status == DMA_COMPLETE)
35 complete(&dma->completion);
36 }
37
38 /**
39 * stm32_timers_dma_burst_read - Read from timers registers using DMA.
40 *
41 * Read from STM32 timers registers using DMA on a single event.
42 * @dev: reference to stm32_timers MFD device
43 * @buf: DMA'able destination buffer
44 * @id: stm32_timers_dmas event identifier (ch[1..4], up, trig or com)
45 * @reg: registers start offset for DMA to read from (like CCRx for capture)
46 * @num_reg: number of registers to read upon each DMA request, starting @reg.
47 * @bursts: number of bursts to read (e.g. like two for pwm period capture)
48 * @tmo_ms: timeout (milliseconds)
49 */
stm32_timers_dma_burst_read(struct device * dev,u32 * buf,enum stm32_timers_dmas id,u32 reg,unsigned int num_reg,unsigned int bursts,unsigned long tmo_ms)50 int stm32_timers_dma_burst_read(struct device *dev, u32 *buf,
51 enum stm32_timers_dmas id, u32 reg,
52 unsigned int num_reg, unsigned int bursts,
53 unsigned long tmo_ms)
54 {
55 struct stm32_timers *ddata = dev_get_drvdata(dev);
56 unsigned long timeout = msecs_to_jiffies(tmo_ms);
57 struct regmap *regmap = ddata->regmap;
58 struct stm32_timers_dma *dma = &ddata->dma;
59 size_t len = num_reg * bursts * sizeof(u32);
60 struct dma_async_tx_descriptor *desc;
61 struct dma_slave_config config;
62 dma_cookie_t cookie;
63 dma_addr_t dma_buf;
64 u32 dbl, dba;
65 long err;
66 int ret;
67
68 /* Sanity check */
69 if (id < STM32_TIMERS_DMA_CH1 || id >= STM32_TIMERS_MAX_DMAS)
70 return -EINVAL;
71
72 if (!num_reg || !bursts || reg > STM32_TIMERS_MAX_REGISTERS ||
73 (reg + num_reg * sizeof(u32)) > STM32_TIMERS_MAX_REGISTERS)
74 return -EINVAL;
75
76 if (!dma->chans[id])
77 return -ENODEV;
78 mutex_lock(&dma->lock);
79
80 /* Select DMA channel in use */
81 dma->chan = dma->chans[id];
82 dma_buf = dma_map_single(dev, buf, len, DMA_FROM_DEVICE);
83 if (dma_mapping_error(dev, dma_buf)) {
84 ret = -ENOMEM;
85 goto unlock;
86 }
87
88 /* Prepare DMA read from timer registers, using DMA burst mode */
89 memset(&config, 0, sizeof(config));
90 config.src_addr = (dma_addr_t)dma->phys_base + TIM_DMAR;
91 config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
92 ret = dmaengine_slave_config(dma->chan, &config);
93 if (ret)
94 goto unmap;
95
96 desc = dmaengine_prep_slave_single(dma->chan, dma_buf, len,
97 DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
98 if (!desc) {
99 ret = -EBUSY;
100 goto unmap;
101 }
102
103 desc->callback = stm32_timers_dma_done;
104 desc->callback_param = dma;
105 cookie = dmaengine_submit(desc);
106 ret = dma_submit_error(cookie);
107 if (ret)
108 goto dma_term;
109
110 reinit_completion(&dma->completion);
111 dma_async_issue_pending(dma->chan);
112
113 /* Setup and enable timer DMA burst mode */
114 dbl = FIELD_PREP(TIM_DCR_DBL, bursts - 1);
115 dba = FIELD_PREP(TIM_DCR_DBA, reg >> 2);
116 ret = regmap_write(regmap, TIM_DCR, dbl | dba);
117 if (ret)
118 goto dma_term;
119
120 /* Clear pending flags before enabling DMA request */
121 ret = regmap_write(regmap, TIM_SR, 0);
122 if (ret)
123 goto dcr_clr;
124
125 ret = regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id],
126 stm32_timers_dier_dmaen[id]);
127 if (ret)
128 goto dcr_clr;
129
130 err = wait_for_completion_interruptible_timeout(&dma->completion,
131 timeout);
132 if (err == 0)
133 ret = -ETIMEDOUT;
134 else if (err < 0)
135 ret = err;
136
137 regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id], 0);
138 regmap_write(regmap, TIM_SR, 0);
139 dcr_clr:
140 regmap_write(regmap, TIM_DCR, 0);
141 dma_term:
142 dmaengine_terminate_all(dma->chan);
143 unmap:
144 dma_unmap_single(dev, dma_buf, len, DMA_FROM_DEVICE);
145 unlock:
146 dma->chan = NULL;
147 mutex_unlock(&dma->lock);
148
149 return ret;
150 }
151 EXPORT_SYMBOL_GPL(stm32_timers_dma_burst_read);
152
153 static const struct regmap_config stm32_timers_regmap_cfg = {
154 .reg_bits = 32,
155 .val_bits = 32,
156 .reg_stride = sizeof(u32),
157 .max_register = STM32_TIMERS_MAX_REGISTERS,
158 };
159
stm32_timers_get_arr_size(struct stm32_timers * ddata)160 static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
161 {
162 u32 arr;
163
164 /* Backup ARR to restore it after getting the maximum value */
165 regmap_read(ddata->regmap, TIM_ARR, &arr);
166
167 /*
168 * Only the available bits will be written so when readback
169 * we get the maximum value of auto reload register
170 */
171 regmap_write(ddata->regmap, TIM_ARR, ~0L);
172 regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr);
173 regmap_write(ddata->regmap, TIM_ARR, arr);
174 }
175
stm32_timers_dma_probe(struct device * dev,struct stm32_timers * ddata)176 static int stm32_timers_dma_probe(struct device *dev,
177 struct stm32_timers *ddata)
178 {
179 int i;
180 int ret = 0;
181 char name[4];
182
183 init_completion(&ddata->dma.completion);
184 mutex_init(&ddata->dma.lock);
185
186 /* Optional DMA support: get valid DMA channel(s) or NULL */
187 for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
188 snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
189 ddata->dma.chans[i] = dma_request_chan(dev, name);
190 }
191 ddata->dma.chans[STM32_TIMERS_DMA_UP] = dma_request_chan(dev, "up");
192 ddata->dma.chans[STM32_TIMERS_DMA_TRIG] = dma_request_chan(dev, "trig");
193 ddata->dma.chans[STM32_TIMERS_DMA_COM] = dma_request_chan(dev, "com");
194
195 for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++) {
196 if (IS_ERR(ddata->dma.chans[i])) {
197 /* Save the first error code to return */
198 if (PTR_ERR(ddata->dma.chans[i]) != -ENODEV && !ret)
199 ret = PTR_ERR(ddata->dma.chans[i]);
200
201 ddata->dma.chans[i] = NULL;
202 }
203 }
204
205 return ret;
206 }
207
stm32_timers_dma_remove(struct device * dev,struct stm32_timers * ddata)208 static void stm32_timers_dma_remove(struct device *dev,
209 struct stm32_timers *ddata)
210 {
211 int i;
212
213 for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++)
214 if (ddata->dma.chans[i])
215 dma_release_channel(ddata->dma.chans[i]);
216 }
217
stm32_timers_probe(struct platform_device * pdev)218 static int stm32_timers_probe(struct platform_device *pdev)
219 {
220 struct device *dev = &pdev->dev;
221 struct stm32_timers *ddata;
222 struct resource *res;
223 void __iomem *mmio;
224 int ret;
225
226 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
227 if (!ddata)
228 return -ENOMEM;
229
230 mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
231 if (IS_ERR(mmio))
232 return PTR_ERR(mmio);
233
234 /* Timer physical addr for DMA */
235 ddata->dma.phys_base = res->start;
236
237 ddata->regmap = devm_regmap_init_mmio_clk(dev, "int", mmio,
238 &stm32_timers_regmap_cfg);
239 if (IS_ERR(ddata->regmap))
240 return PTR_ERR(ddata->regmap);
241
242 ddata->clk = devm_clk_get(dev, NULL);
243 if (IS_ERR(ddata->clk))
244 return PTR_ERR(ddata->clk);
245
246 stm32_timers_get_arr_size(ddata);
247
248 ret = stm32_timers_dma_probe(dev, ddata);
249 if (ret) {
250 stm32_timers_dma_remove(dev, ddata);
251 return ret;
252 }
253
254 platform_set_drvdata(pdev, ddata);
255
256 ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
257 if (ret)
258 stm32_timers_dma_remove(dev, ddata);
259
260 return ret;
261 }
262
stm32_timers_remove(struct platform_device * pdev)263 static int stm32_timers_remove(struct platform_device *pdev)
264 {
265 struct stm32_timers *ddata = platform_get_drvdata(pdev);
266
267 /*
268 * Don't use devm_ here: enfore of_platform_depopulate() happens before
269 * DMA are released, to avoid race on DMA.
270 */
271 of_platform_depopulate(&pdev->dev);
272 stm32_timers_dma_remove(&pdev->dev, ddata);
273
274 return 0;
275 }
276
277 static const struct of_device_id stm32_timers_of_match[] = {
278 { .compatible = "st,stm32-timers", },
279 { /* end node */ },
280 };
281 MODULE_DEVICE_TABLE(of, stm32_timers_of_match);
282
283 static struct platform_driver stm32_timers_driver = {
284 .probe = stm32_timers_probe,
285 .remove = stm32_timers_remove,
286 .driver = {
287 .name = "stm32-timers",
288 .of_match_table = stm32_timers_of_match,
289 },
290 };
291 module_platform_driver(stm32_timers_driver);
292
293 MODULE_DESCRIPTION("STMicroelectronics STM32 Timers");
294 MODULE_LICENSE("GPL v2");
295
