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 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 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 */ 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 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 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 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 } 102 103 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 } 116 117 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 } 130 131 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 const 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_function ftm_quaddec_count_functions[] = { 175 [FTM_QUADDEC_COUNT_ENCODER_MODE_1] = COUNTER_FUNCTION_QUADRATURE_X4 176 }; 177 178 static int ftm_quaddec_count_read(struct counter_device *counter, 179 struct counter_count *count, 180 unsigned long *val) 181 { 182 struct ftm_quaddec *const ftm = counter->priv; 183 uint32_t cntval; 184 185 ftm_read(ftm, FTM_CNT, &cntval); 186 187 *val = cntval; 188 189 return 0; 190 } 191 192 static int ftm_quaddec_count_write(struct counter_device *counter, 193 struct counter_count *count, 194 const unsigned long val) 195 { 196 struct ftm_quaddec *const ftm = counter->priv; 197 198 if (val != 0) { 199 dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n"); 200 return -EINVAL; 201 } 202 203 ftm_reset_counter(ftm); 204 205 return 0; 206 } 207 208 static int ftm_quaddec_count_function_get(struct counter_device *counter, 209 struct counter_count *count, 210 size_t *function) 211 { 212 *function = FTM_QUADDEC_COUNT_ENCODER_MODE_1; 213 214 return 0; 215 } 216 217 static int ftm_quaddec_action_get(struct counter_device *counter, 218 struct counter_count *count, 219 struct counter_synapse *synapse, 220 size_t *action) 221 { 222 *action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES; 223 224 return 0; 225 } 226 227 static const struct counter_ops ftm_quaddec_cnt_ops = { 228 .count_read = ftm_quaddec_count_read, 229 .count_write = ftm_quaddec_count_write, 230 .function_get = ftm_quaddec_count_function_get, 231 .action_get = ftm_quaddec_action_get, 232 }; 233 234 static struct counter_signal ftm_quaddec_signals[] = { 235 { 236 .id = 0, 237 .name = "Channel 1 Phase A" 238 }, 239 { 240 .id = 1, 241 .name = "Channel 1 Phase B" 242 } 243 }; 244 245 static struct counter_synapse ftm_quaddec_count_synapses[] = { 246 { 247 .actions_list = ftm_quaddec_synapse_actions, 248 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions), 249 .signal = &ftm_quaddec_signals[0] 250 }, 251 { 252 .actions_list = ftm_quaddec_synapse_actions, 253 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions), 254 .signal = &ftm_quaddec_signals[1] 255 } 256 }; 257 258 static const struct counter_count_ext ftm_quaddec_count_ext[] = { 259 COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum), 260 COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum), 261 }; 262 263 static struct counter_count ftm_quaddec_counts = { 264 .id = 0, 265 .name = "Channel 1 Count", 266 .functions_list = ftm_quaddec_count_functions, 267 .num_functions = ARRAY_SIZE(ftm_quaddec_count_functions), 268 .synapses = ftm_quaddec_count_synapses, 269 .num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses), 270 .ext = ftm_quaddec_count_ext, 271 .num_ext = ARRAY_SIZE(ftm_quaddec_count_ext) 272 }; 273 274 static int ftm_quaddec_probe(struct platform_device *pdev) 275 { 276 struct ftm_quaddec *ftm; 277 278 struct device_node *node = pdev->dev.of_node; 279 struct resource *io; 280 int ret; 281 282 ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL); 283 if (!ftm) 284 return -ENOMEM; 285 286 platform_set_drvdata(pdev, ftm); 287 288 io = platform_get_resource(pdev, IORESOURCE_MEM, 0); 289 if (!io) { 290 dev_err(&pdev->dev, "Failed to get memory region\n"); 291 return -ENODEV; 292 } 293 294 ftm->pdev = pdev; 295 ftm->big_endian = of_property_read_bool(node, "big-endian"); 296 ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io)); 297 298 if (!ftm->ftm_base) { 299 dev_err(&pdev->dev, "Failed to map memory region\n"); 300 return -EINVAL; 301 } 302 ftm->counter.name = dev_name(&pdev->dev); 303 ftm->counter.parent = &pdev->dev; 304 ftm->counter.ops = &ftm_quaddec_cnt_ops; 305 ftm->counter.counts = &ftm_quaddec_counts; 306 ftm->counter.num_counts = 1; 307 ftm->counter.signals = ftm_quaddec_signals; 308 ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals); 309 ftm->counter.priv = ftm; 310 311 mutex_init(&ftm->ftm_quaddec_mutex); 312 313 ftm_quaddec_init(ftm); 314 315 ret = devm_add_action_or_reset(&pdev->dev, ftm_quaddec_disable, ftm); 316 if (ret) 317 return ret; 318 319 ret = devm_counter_register(&pdev->dev, &ftm->counter); 320 if (ret) 321 return ret; 322 323 return 0; 324 } 325 326 static const struct of_device_id ftm_quaddec_match[] = { 327 { .compatible = "fsl,ftm-quaddec" }, 328 {}, 329 }; 330 331 static struct platform_driver ftm_quaddec_driver = { 332 .driver = { 333 .name = "ftm-quaddec", 334 .of_match_table = ftm_quaddec_match, 335 }, 336 .probe = ftm_quaddec_probe, 337 }; 338 339 module_platform_driver(ftm_quaddec_driver); 340 341 MODULE_LICENSE("GPL"); 342 MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com>"); 343 MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>"); 344