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 #include <linux/types.h>
  18
  19 #define FTM_FIELD_UPDATE(ftm, offset, mask, val)                        \
  20         ({                                                              \
  21                 uint32_t flags;                                         \
  22                 ftm_read(ftm, offset, &flags);                          \
  23                 flags &= ~mask;                                         \
  24                 flags |= FIELD_PREP(mask, val);                         \
  25                 ftm_write(ftm, offset, flags);                          \
  26         })
  27
  28 struct ftm_quaddec {
  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, u32 *cnt_mode)
 119 {
 120         struct ftm_quaddec *ftm = counter_priv(counter);
 121         uint32_t scflags;
 122
 123         ftm_read(ftm, FTM_SC, &scflags);
 124
 125         *cnt_mode = FIELD_GET(FTM_SC_PS_MASK, scflags);
 126
 127         return 0;
 128 }
 129
 130 static int ftm_quaddec_set_prescaler(struct counter_device *counter,
 131                                      struct counter_count *count, u32 cnt_mode)
 132 {
 133         struct ftm_quaddec *ftm = counter_priv(counter);
 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 const enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
 153         COUNTER_SYNAPSE_ACTION_BOTH_EDGES
 154 };
 155
 156 static const enum counter_function ftm_quaddec_count_functions[] = {
 157         COUNTER_FUNCTION_QUADRATURE_X4
 158 };
 159
 160 static int ftm_quaddec_count_read(struct counter_device *counter,
 161                                   struct counter_count *count,
 162                                   u64 *val)
 163 {
 164         struct ftm_quaddec *const ftm = counter_priv(counter);
 165         uint32_t cntval;
 166
 167         ftm_read(ftm, FTM_CNT, &cntval);
 168
 169         *val = cntval;
 170
 171         return 0;
 172 }
 173
 174 static int ftm_quaddec_count_write(struct counter_device *counter,
 175                                    struct counter_count *count,
 176                                    const u64 val)
 177 {
 178         struct ftm_quaddec *const ftm = counter_priv(counter);
 179
 180         if (val != 0) {
 181                 dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
 182                 return -EINVAL;
 183         }
 184
 185         ftm_reset_counter(ftm);
 186
 187         return 0;
 188 }
 189
 190 static int ftm_quaddec_count_function_read(struct counter_device *counter,
 191                                            struct counter_count *count,
 192                                            enum counter_function *function)
 193 {
 194         *function = COUNTER_FUNCTION_QUADRATURE_X4;
 195
 196         return 0;
 197 }
 198
 199 static int ftm_quaddec_action_read(struct counter_device *counter,
 200                                    struct counter_count *count,
 201                                    struct counter_synapse *synapse,
 202                                    enum counter_synapse_action *action)
 203 {
 204         *action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
 205
 206         return 0;
 207 }
 208
 209 static const struct counter_ops ftm_quaddec_cnt_ops = {
 210         .count_read = ftm_quaddec_count_read,
 211         .count_write = ftm_quaddec_count_write,
 212         .function_read = ftm_quaddec_count_function_read,
 213         .action_read = ftm_quaddec_action_read,
 214 };
 215
 216 static struct counter_signal ftm_quaddec_signals[] = {
 217         {
 218                 .id = 0,
 219                 .name = "Channel 1 Phase A"
 220         },
 221         {
 222                 .id = 1,
 223                 .name = "Channel 1 Phase B"
 224         }
 225 };
 226
 227 static struct counter_synapse ftm_quaddec_count_synapses[] = {
 228         {
 229                 .actions_list = ftm_quaddec_synapse_actions,
 230                 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
 231                 .signal = &ftm_quaddec_signals[0]
 232         },
 233         {
 234                 .actions_list = ftm_quaddec_synapse_actions,
 235                 .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
 236                 .signal = &ftm_quaddec_signals[1]
 237         }
 238 };
 239
 240 static DEFINE_COUNTER_ENUM(ftm_quaddec_prescaler_enum, ftm_quaddec_prescaler);
 241
 242 static struct counter_comp ftm_quaddec_count_ext[] = {
 243         COUNTER_COMP_COUNT_ENUM("prescaler", ftm_quaddec_get_prescaler,
 244                                 ftm_quaddec_set_prescaler,
 245                                 ftm_quaddec_prescaler_enum),
 246 };
 247
 248 static struct counter_count ftm_quaddec_counts = {
 249         .id = 0,
 250         .name = "Channel 1 Count",
 251         .functions_list = ftm_quaddec_count_functions,
 252         .num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
 253         .synapses = ftm_quaddec_count_synapses,
 254         .num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
 255         .ext = ftm_quaddec_count_ext,
 256         .num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
 257 };
 258
 259 static int ftm_quaddec_probe(struct platform_device *pdev)
 260 {
 261         struct counter_device *counter;
 262         struct ftm_quaddec *ftm;
 263
 264         struct device_node *node = pdev->dev.of_node;
 265         struct resource *io;
 266         int ret;
 267
 268         counter = devm_counter_alloc(&pdev->dev, sizeof(*ftm));
 269         if (!counter)
 270                 return -ENOMEM;
 271         ftm = counter_priv(counter);
 272
 273         io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 274         if (!io) {
 275                 dev_err(&pdev->dev, "Failed to get memory region\n");
 276                 return -ENODEV;
 277         }
 278
 279         ftm->pdev = pdev;
 280         ftm->big_endian = of_property_read_bool(node, "big-endian");
 281         ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
 282
 283         if (!ftm->ftm_base) {
 284                 dev_err(&pdev->dev, "Failed to map memory region\n");
 285                 return -EINVAL;
 286         }
 287         counter->name = dev_name(&pdev->dev);
 288         counter->parent = &pdev->dev;
 289         counter->ops = &ftm_quaddec_cnt_ops;
 290         counter->counts = &ftm_quaddec_counts;
 291         counter->num_counts = 1;
 292         counter->signals = ftm_quaddec_signals;
 293         counter->num_signals = ARRAY_SIZE(ftm_quaddec_signals);
 294
 295         mutex_init(&ftm->ftm_quaddec_mutex);
 296
 297         ftm_quaddec_init(ftm);
 298
 299         ret = devm_add_action_or_reset(&pdev->dev, ftm_quaddec_disable, ftm);
 300         if (ret)
 301                 return ret;
 302
 303         ret = devm_counter_add(&pdev->dev, counter);
 304         if (ret)
 305                 return dev_err_probe(&pdev->dev, ret, "Failed to add counter\n");
 306
 307         return 0;
 308 }
 309
 310 static const struct of_device_id ftm_quaddec_match[] = {
 311         { .compatible = "fsl,ftm-quaddec" },
 312         {},
 313 };
 314
 315 static struct platform_driver ftm_quaddec_driver = {
 316         .driver = {
 317                 .name = "ftm-quaddec",
 318                 .of_match_table = ftm_quaddec_match,
 319         },
 320         .probe = ftm_quaddec_probe,
 321 };
 322
 323 module_platform_driver(ftm_quaddec_driver);
 324
 325 MODULE_LICENSE("GPL");
 326 MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com>");
 327 MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>");