drivers/counter/ftm-quaddec.c

   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(struct ftm_quaddec *ftm)
 104 {
 105         ftm_clear_write_protection(ftm);
 106         ftm_write(ftm, FTM_MODE, 0);
 107         ftm_write(ftm, FTM_QDCTRL, 0);
 108         /*
 109          * This is enough to disable the counter. No clock has been
 110          * selected by writing to FTM_SC in init()
 111          */
 112         ftm_set_write_protection(ftm);
 113 }
 114
 115 static int ftm_quaddec_get_prescaler(struct counter_device *counter,
 116                                      struct counter_count *count,
 117                                      size_t *cnt_mode)
 118 {
 119         struct ftm_quaddec *ftm = counter->priv;
 120         uint32_t scflags;
 121
 122         ftm_read(ftm, FTM_SC, &scflags);
 123
 124         *cnt_mode = FIELD_GET(FTM_SC_PS_MASK, scflags);
 125
 126         return 0;
 127 }
 128
 129 static int ftm_quaddec_set_prescaler(struct counter_device *counter,
 130                                      struct counter_count *count,
 131                                      size_t cnt_mode)
 132 {
 133         struct ftm_quaddec *ftm = counter->priv;
 134
 135         mutex_lock(&ftm->ftm_quaddec_mutex);
 136
 137         ftm_clear_write_protection(ftm);
 138         FTM_FIELD_UPDATE(ftm, FTM_SC, FTM_SC_PS_MASK, cnt_mode);
 139         ftm_set_write_protection(ftm);
 140
 141         /* Also resets the counter as it is undefined anyway now */
 142         ftm_reset_counter(ftm);
 143
 144         mutex_unlock(&ftm->ftm_quaddec_mutex);
 145         return 0;
 146 }
 147
 148 static const char * const ftm_quaddec_prescaler[] = {
 149         "1", "2", "4", "8", "16", "32", "64", "128"
 150 };
 151
 152 static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
 153         .items = ftm_quaddec_prescaler,
 154         .num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
 155         .get = ftm_quaddec_get_prescaler,
 156         .set = ftm_quaddec_set_prescaler
 157 };
 158
 159 enum ftm_quaddec_synapse_action {
 160         FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
 161 };
 162
 163 static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
 164         [FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
 165         COUNTER_SYNAPSE_ACTION_BOTH_EDGES
 166 };
 167
 168 enum ftm_quaddec_count_function {
 169         FTM_QUADDEC_COUNT_ENCODER_MODE_1,
 170 };
 171
 172 static const enum counter_count_function ftm_quaddec_count_functions[] = {
 173         [FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
 174         COUNTER_COUNT_FUNCTION_QUADRATURE_X4
 175 };
 176
 177 static int ftm_quaddec_count_read(struct counter_device *counter,
 178                                   struct counter_count *count,
 179                                   struct counter_count_read_value *val)
 180 {
 181         struct ftm_quaddec *const ftm = counter->priv;
 182         uint32_t cntval;
 183
 184         ftm_read(ftm, FTM_CNT, &cntval);
 185
 186         counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);
 187
 188         return 0;
 189 }
 190
 191 static int ftm_quaddec_count_write(struct counter_device *counter,
 192                                    struct counter_count *count,
 193                                    struct counter_count_write_value *val)
 194 {
 195         struct ftm_quaddec *const ftm = counter->priv;
 196         u32 cnt;
 197         int err;
 198
 199         err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
 200         if (err)
 201                 return err;
 202
 203         if (cnt != 0) {
 204                 dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
 205                 return -EINVAL;
 206         }
 207
 208         ftm_reset_counter(ftm);
 209
 210         return 0;
 211 }
 212
 213 static int ftm_quaddec_count_function_get(struct counter_device *counter,
 214                                           struct counter_count *count,
 215                                           size_t *function)
 216 {
 217         *function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
 218
 219         return 0;
 220 }
 221
 222 static int ftm_quaddec_action_get(struct counter_device *counter,
 223                                   struct counter_count *count,
 224                                   struct counter_synapse *synapse,
 225                                   size_t *action)
 226 {
 227         *action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
 228
 229         return 0;
 230 }
 231
 232 static const struct counter_ops ftm_quaddec_cnt_ops = {
 233         .count_read = ftm_quaddec_count_read,
 234         .count_write = ftm_quaddec_count_write,
 235         .function_get = ftm_quaddec_count_function_get,
 236         .action_get = ftm_quaddec_action_get,
 237 };
 238
 239 static struct counter_signal ftm_quaddec_signals[] = {
 240         {
 241                 .id = 0,
 242                 .name = "Channel 1 Phase A"
 243         },
 244         {
 245                 .id = 1,
 246                 .name = "Channel 1 Phase B"
 247         }
 248 };
 249
 250 static struct counter_synapse ftm_quaddec_count_synapses[] = {
 251         {
 252                 .actions_list = ftm_quaddec_synapse_actions,
 253                 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
 254                 .signal = &ftm_quaddec_signals[0]
 255         },
 256         {
 257                 .actions_list = ftm_quaddec_synapse_actions,
 258                 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
 259                 .signal = &ftm_quaddec_signals[1]
 260         }
 261 };
 262
 263 static const struct counter_count_ext ftm_quaddec_count_ext[] = {
 264         COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
 265         COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
 266 };
 267
 268 static struct counter_count ftm_quaddec_counts = {
 269         .id = 0,
 270         .name = "Channel 1 Count",
 271         .functions_list = ftm_quaddec_count_functions,
 272         .num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
 273         .synapses = ftm_quaddec_count_synapses,
 274         .num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
 275         .ext = ftm_quaddec_count_ext,
 276         .num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
 277 };
 278
 279 static int ftm_quaddec_probe(struct platform_device *pdev)
 280 {
 281         struct ftm_quaddec *ftm;
 282
 283         struct device_node *node = pdev->dev.of_node;
 284         struct resource *io;
 285         int ret;
 286
 287         ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
 288         if (!ftm)
 289                 return -ENOMEM;
 290
 291         platform_set_drvdata(pdev, ftm);
 292
 293         io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 294         if (!io) {
 295                 dev_err(&pdev->dev, "Failed to get memory region\n");
 296                 return -ENODEV;
 297         }
 298
 299         ftm->pdev = pdev;
 300         ftm->big_endian = of_property_read_bool(node, "big-endian");
 301         ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
 302
 303         if (!ftm->ftm_base) {
 304                 dev_err(&pdev->dev, "Failed to map memory region\n");
 305                 return -EINVAL;
 306         }
 307         ftm->counter.name = dev_name(&pdev->dev);
 308         ftm->counter.parent = &pdev->dev;
 309         ftm->counter.ops = &ftm_quaddec_cnt_ops;
 310         ftm->counter.counts = &ftm_quaddec_counts;
 311         ftm->counter.num_counts = 1;
 312         ftm->counter.signals = ftm_quaddec_signals;
 313         ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
 314         ftm->counter.priv = ftm;
 315
 316         mutex_init(&ftm->ftm_quaddec_mutex);
 317
 318         ftm_quaddec_init(ftm);
 319
 320         ret = counter_register(&ftm->counter);
 321         if (ret)
 322                 ftm_quaddec_disable(ftm);
 323
 324         return ret;
 325 }
 326
 327 static int ftm_quaddec_remove(struct platform_device *pdev)
 328 {
 329         struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
 330
 331         counter_unregister(&ftm->counter);
 332
 333         ftm_quaddec_disable(ftm);
 334
 335         return 0;
 336 }
 337
 338 static const struct of_device_id ftm_quaddec_match[] = {
 339         { .compatible = "fsl,ftm-quaddec" },
 340         {},
 341 };
 342
 343 static struct platform_driver ftm_quaddec_driver = {
 344         .driver = {
 345                 .name = "ftm-quaddec",
 346                 .of_match_table = ftm_quaddec_match,
 347         },
 348         .probe = ftm_quaddec_probe,
 349         .remove = ftm_quaddec_remove,
 350 };
 351
 352 module_platform_driver(ftm_quaddec_driver);
 353
 354 MODULE_LICENSE("GPL");
 355 MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com>");
 356 MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>");