1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Flex Timer Module Quadrature decoder
4 *
5 * This module implements a driver for decoding the FTM quadrature
6 * of ex. a LS1021A
7 */
8
9 #include <linux/fsl/ftm.h>
10 #include <linux/module.h>
11 #include <linux/platform_device.h>
12 #include <linux/of.h>
13 #include <linux/io.h>
14 #include <linux/mutex.h>
15 #include <linux/counter.h>
16 #include <linux/bitfield.h>
17
18 #define FTM_FIELD_UPDATE(ftm, offset, mask, val) \
19 ({ \
20 uint32_t flags; \
21 ftm_read(ftm, offset, &flags); \
22 flags &= ~mask; \
23 flags |= FIELD_PREP(mask, val); \
24 ftm_write(ftm, offset, flags); \
25 })
26
27 struct ftm_quaddec {
28 struct counter_device counter;
29 struct platform_device *pdev;
30 void __iomem *ftm_base;
31 bool big_endian;
32 struct mutex ftm_quaddec_mutex;
33 };
34
ftm_read(struct ftm_quaddec * ftm,uint32_t offset,uint32_t * data)35 static void ftm_read(struct ftm_quaddec *ftm, uint32_t offset, uint32_t *data)
36 {
37 if (ftm->big_endian)
38 *data = ioread32be(ftm->ftm_base + offset);
39 else
40 *data = ioread32(ftm->ftm_base + offset);
41 }
42
ftm_write(struct ftm_quaddec * ftm,uint32_t offset,uint32_t data)43 static void ftm_write(struct ftm_quaddec *ftm, uint32_t offset, uint32_t data)
44 {
45 if (ftm->big_endian)
46 iowrite32be(data, ftm->ftm_base + offset);
47 else
48 iowrite32(data, ftm->ftm_base + offset);
49 }
50
51 /* Hold mutex before modifying write protection state */
ftm_clear_write_protection(struct ftm_quaddec * ftm)52 static void ftm_clear_write_protection(struct ftm_quaddec *ftm)
53 {
54 uint32_t flag;
55
56 /* First see if it is enabled */
57 ftm_read(ftm, FTM_FMS, &flag);
58
59 if (flag & FTM_FMS_WPEN)
60 FTM_FIELD_UPDATE(ftm, FTM_MODE, FTM_MODE_WPDIS, 1);
61 }
62
ftm_set_write_protection(struct ftm_quaddec * ftm)63 static void ftm_set_write_protection(struct ftm_quaddec *ftm)
64 {
65 FTM_FIELD_UPDATE(ftm, FTM_FMS, FTM_FMS_WPEN, 1);
66 }
67
ftm_reset_counter(struct ftm_quaddec * ftm)68 static void ftm_reset_counter(struct ftm_quaddec *ftm)
69 {
70 /* Reset hardware counter to CNTIN */
71 ftm_write(ftm, FTM_CNT, 0x0);
72 }
73
ftm_quaddec_init(struct ftm_quaddec * ftm)74 static void ftm_quaddec_init(struct ftm_quaddec *ftm)
75 {
76 ftm_clear_write_protection(ftm);
77
78 /*
79 * Do not write in the region from the CNTIN register through the
80 * PWMLOAD register when FTMEN = 0.
81 * Also reset other fields to zero
82 */
83 ftm_write(ftm, FTM_MODE, FTM_MODE_FTMEN);
84 ftm_write(ftm, FTM_CNTIN, 0x0000);
85 ftm_write(ftm, FTM_MOD, 0xffff);
86 ftm_write(ftm, FTM_CNT, 0x0);
87 /* Set prescaler, reset other fields to zero */
88 ftm_write(ftm, FTM_SC, FTM_SC_PS_1);
89
90 /* Select quad mode, reset other fields to zero */
91 ftm_write(ftm, FTM_QDCTRL, FTM_QDCTRL_QUADEN);
92
93 /* Unused features and reset to default section */
94 ftm_write(ftm, FTM_POL, 0x0);
95 ftm_write(ftm, FTM_FLTCTRL, 0x0);
96 ftm_write(ftm, FTM_SYNCONF, 0x0);
97 ftm_write(ftm, FTM_SYNC, 0xffff);
98
99 /* Lock the FTM */
100 ftm_set_write_protection(ftm);
101 }
102
ftm_quaddec_disable(void * ftm)103 static void ftm_quaddec_disable(void *ftm)
104 {
105 struct ftm_quaddec *ftm_qua = ftm;
106
107 ftm_clear_write_protection(ftm_qua);
108 ftm_write(ftm_qua, FTM_MODE, 0);
109 ftm_write(ftm_qua, FTM_QDCTRL, 0);
110 /*
111 * This is enough to disable the counter. No clock has been
112 * selected by writing to FTM_SC in init()
113 */
114 ftm_set_write_protection(ftm_qua);
115 }
116
ftm_quaddec_get_prescaler(struct counter_device * counter,struct counter_count * count,size_t * cnt_mode)117 static int ftm_quaddec_get_prescaler(struct counter_device *counter,
118 struct counter_count *count,
119 size_t *cnt_mode)
120 {
121 struct ftm_quaddec *ftm = counter->priv;
122 uint32_t scflags;
123
124 ftm_read(ftm, FTM_SC, &scflags);
125
126 *cnt_mode = FIELD_GET(FTM_SC_PS_MASK, scflags);
127
128 return 0;
129 }
130
ftm_quaddec_set_prescaler(struct counter_device * counter,struct counter_count * count,size_t cnt_mode)131 static int ftm_quaddec_set_prescaler(struct counter_device *counter,
132 struct counter_count *count,
133 size_t cnt_mode)
134 {
135 struct ftm_quaddec *ftm = counter->priv;
136
137 mutex_lock(&ftm->ftm_quaddec_mutex);
138
139 ftm_clear_write_protection(ftm);
140 FTM_FIELD_UPDATE(ftm, FTM_SC, FTM_SC_PS_MASK, cnt_mode);
141 ftm_set_write_protection(ftm);
142
143 /* Also resets the counter as it is undefined anyway now */
144 ftm_reset_counter(ftm);
145
146 mutex_unlock(&ftm->ftm_quaddec_mutex);
147 return 0;
148 }
149
150 static const char * const ftm_quaddec_prescaler[] = {
151 "1", "2", "4", "8", "16", "32", "64", "128"
152 };
153
154 static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
155 .items = ftm_quaddec_prescaler,
156 .num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
157 .get = ftm_quaddec_get_prescaler,
158 .set = ftm_quaddec_set_prescaler
159 };
160
161 enum ftm_quaddec_synapse_action {
162 FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
163 };
164
165 static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
166 [FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
167 COUNTER_SYNAPSE_ACTION_BOTH_EDGES
168 };
169
170 enum ftm_quaddec_count_function {
171 FTM_QUADDEC_COUNT_ENCODER_MODE_1,
172 };
173
174 static const enum counter_count_function ftm_quaddec_count_functions[] = {
175 [FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
176 COUNTER_COUNT_FUNCTION_QUADRATURE_X4
177 };
178
ftm_quaddec_count_read(struct counter_device * counter,struct counter_count * count,struct counter_count_read_value * val)179 static int ftm_quaddec_count_read(struct counter_device *counter,
180 struct counter_count *count,
181 struct counter_count_read_value *val)
182 {
183 struct ftm_quaddec *const ftm = counter->priv;
184 uint32_t cntval;
185
186 ftm_read(ftm, FTM_CNT, &cntval);
187
188 counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);
189
190 return 0;
191 }
192
ftm_quaddec_count_write(struct counter_device * counter,struct counter_count * count,struct counter_count_write_value * val)193 static int ftm_quaddec_count_write(struct counter_device *counter,
194 struct counter_count *count,
195 struct counter_count_write_value *val)
196 {
197 struct ftm_quaddec *const ftm = counter->priv;
198 u32 cnt;
199 int err;
200
201 err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
202 if (err)
203 return err;
204
205 if (cnt != 0) {
206 dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
207 return -EINVAL;
208 }
209
210 ftm_reset_counter(ftm);
211
212 return 0;
213 }
214
ftm_quaddec_count_function_get(struct counter_device * counter,struct counter_count * count,size_t * function)215 static int ftm_quaddec_count_function_get(struct counter_device *counter,
216 struct counter_count *count,
217 size_t *function)
218 {
219 *function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
220
221 return 0;
222 }
223
ftm_quaddec_action_get(struct counter_device * counter,struct counter_count * count,struct counter_synapse * synapse,size_t * action)224 static int ftm_quaddec_action_get(struct counter_device *counter,
225 struct counter_count *count,
226 struct counter_synapse *synapse,
227 size_t *action)
228 {
229 *action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
230
231 return 0;
232 }
233
234 static const struct counter_ops ftm_quaddec_cnt_ops = {
235 .count_read = ftm_quaddec_count_read,
236 .count_write = ftm_quaddec_count_write,
237 .function_get = ftm_quaddec_count_function_get,
238 .action_get = ftm_quaddec_action_get,
239 };
240
241 static struct counter_signal ftm_quaddec_signals[] = {
242 {
243 .id = 0,
244 .name = "Channel 1 Phase A"
245 },
246 {
247 .id = 1,
248 .name = "Channel 1 Phase B"
249 }
250 };
251
252 static struct counter_synapse ftm_quaddec_count_synapses[] = {
253 {
254 .actions_list = ftm_quaddec_synapse_actions,
255 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
256 .signal = &ftm_quaddec_signals[0]
257 },
258 {
259 .actions_list = ftm_quaddec_synapse_actions,
260 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
261 .signal = &ftm_quaddec_signals[1]
262 }
263 };
264
265 static const struct counter_count_ext ftm_quaddec_count_ext[] = {
266 COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
267 COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
268 };
269
270 static struct counter_count ftm_quaddec_counts = {
271 .id = 0,
272 .name = "Channel 1 Count",
273 .functions_list = ftm_quaddec_count_functions,
274 .num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
275 .synapses = ftm_quaddec_count_synapses,
276 .num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
277 .ext = ftm_quaddec_count_ext,
278 .num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
279 };
280
ftm_quaddec_probe(struct platform_device * pdev)281 static int ftm_quaddec_probe(struct platform_device *pdev)
282 {
283 struct ftm_quaddec *ftm;
284
285 struct device_node *node = pdev->dev.of_node;
286 struct resource *io;
287 int ret;
288
289 ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
290 if (!ftm)
291 return -ENOMEM;
292
293 platform_set_drvdata(pdev, ftm);
294
295 io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
296 if (!io) {
297 dev_err(&pdev->dev, "Failed to get memory region\n");
298 return -ENODEV;
299 }
300
301 ftm->pdev = pdev;
302 ftm->big_endian = of_property_read_bool(node, "big-endian");
303 ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
304
305 if (!ftm->ftm_base) {
306 dev_err(&pdev->dev, "Failed to map memory region\n");
307 return -EINVAL;
308 }
309 ftm->counter.name = dev_name(&pdev->dev);
310 ftm->counter.parent = &pdev->dev;
311 ftm->counter.ops = &ftm_quaddec_cnt_ops;
312 ftm->counter.counts = &ftm_quaddec_counts;
313 ftm->counter.num_counts = 1;
314 ftm->counter.signals = ftm_quaddec_signals;
315 ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
316 ftm->counter.priv = ftm;
317
318 mutex_init(&ftm->ftm_quaddec_mutex);
319
320 ftm_quaddec_init(ftm);
321
322 ret = devm_add_action_or_reset(&pdev->dev, ftm_quaddec_disable, ftm);
323 if (ret)
324 return ret;
325
326 ret = devm_counter_register(&pdev->dev, &ftm->counter);
327 if (ret)
328 return ret;
329
330 return 0;
331 }
332
333 static const struct of_device_id ftm_quaddec_match[] = {
334 { .compatible = "fsl,ftm-quaddec" },
335 {},
336 };
337
338 static struct platform_driver ftm_quaddec_driver = {
339 .driver = {
340 .name = "ftm-quaddec",
341 .of_match_table = ftm_quaddec_match,
342 },
343 .probe = ftm_quaddec_probe,
344 };
345
346 module_platform_driver(ftm_quaddec_driver);
347
348 MODULE_LICENSE("GPL");
349 MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com>");
350 MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>");
351