drivers/iio/adc/spear_adc.c

   1 /*
   2  * ST SPEAr ADC driver
   3  *
   4  * Copyright 2012 Stefan Roese <sr@denx.de>
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/device.h>
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/io.h>
  16 #include <linux/clk.h>
  17 #include <linux/err.h>
  18 #include <linux/completion.h>
  19 #include <linux/of.h>
  20 #include <linux/of_address.h>
  21
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24
  25 /* SPEAR registers definitions */
  26 #define SPEAR600_ADC_SCAN_RATE_LO(x)    ((x) & 0xFFFF)
  27 #define SPEAR600_ADC_SCAN_RATE_HI(x)    (((x) >> 0x10) & 0xFFFF)
  28 #define SPEAR_ADC_CLK_LOW(x)            (((x) & 0xf) << 0)
  29 #define SPEAR_ADC_CLK_HIGH(x)           (((x) & 0xf) << 4)
  30
  31 /* Bit definitions for SPEAR_ADC_STATUS */
  32 #define SPEAR_ADC_STATUS_START_CONVERSION       BIT(0)
  33 #define SPEAR_ADC_STATUS_CHANNEL_NUM(x)         ((x) << 1)
  34 #define SPEAR_ADC_STATUS_ADC_ENABLE             BIT(4)
  35 #define SPEAR_ADC_STATUS_AVG_SAMPLE(x)          ((x) << 5)
  36 #define SPEAR_ADC_STATUS_VREF_INTERNAL          BIT(9)
  37
  38 #define SPEAR_ADC_DATA_MASK             0x03ff
  39 #define SPEAR_ADC_DATA_BITS             10
  40
  41 #define SPEAR_ADC_MOD_NAME "spear-adc"
  42
  43 #define SPEAR_ADC_CHANNEL_NUM           8
  44
  45 #define SPEAR_ADC_CLK_MIN                       2500000
  46 #define SPEAR_ADC_CLK_MAX                       20000000
  47
  48 struct adc_regs_spear3xx {
  49         u32 status;
  50         u32 average;
  51         u32 scan_rate;
  52         u32 clk;        /* Not avail for 1340 & 1310 */
  53         u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
  54         u32 ch_data[SPEAR_ADC_CHANNEL_NUM];
  55 };
  56
  57 struct chan_data {
  58         u32 lsb;
  59         u32 msb;
  60 };
  61
  62 struct adc_regs_spear6xx {
  63         u32 status;
  64         u32 pad[2];
  65         u32 clk;
  66         u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
  67         struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM];
  68         u32 scan_rate_lo;
  69         u32 scan_rate_hi;
  70         struct chan_data average;
  71 };
  72
  73 struct spear_adc_state {
  74         struct device_node *np;
  75         struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
  76         struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
  77         struct clk *clk;
  78         struct completion completion;
  79         u32 current_clk;
  80         u32 sampling_freq;
  81         u32 avg_samples;
  82         u32 vref_external;
  83         u32 value;
  84 };
  85
  86 /*
  87  * Functions to access some SPEAr ADC register. Abstracted into
  88  * static inline functions, because of different register offsets
  89  * on different SoC variants (SPEAr300 vs SPEAr600 etc).
  90  */
  91 static void spear_adc_set_status(struct spear_adc_state *st, u32 val)
  92 {
  93         __raw_writel(val, &st->adc_base_spear6xx->status);
  94 }
  95
  96 static void spear_adc_set_clk(struct spear_adc_state *st, u32 val)
  97 {
  98         u32 clk_high, clk_low, count;
  99         u32 apb_clk = clk_get_rate(st->clk);
 100
 101         count = DIV_ROUND_UP(apb_clk, val);
 102         clk_low = count / 2;
 103         clk_high = count - clk_low;
 104         st->current_clk = apb_clk / count;
 105
 106         __raw_writel(SPEAR_ADC_CLK_LOW(clk_low) | SPEAR_ADC_CLK_HIGH(clk_high),
 107                      &st->adc_base_spear6xx->clk);
 108 }
 109
 110 static void spear_adc_set_ctrl(struct spear_adc_state *st, int n,
 111                                u32 val)
 112 {
 113         __raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]);
 114 }
 115
 116 static u32 spear_adc_get_average(struct spear_adc_state *st)
 117 {
 118         if (of_device_is_compatible(st->np, "st,spear600-adc")) {
 119                 return __raw_readl(&st->adc_base_spear6xx->average.msb) &
 120                         SPEAR_ADC_DATA_MASK;
 121         } else {
 122                 return __raw_readl(&st->adc_base_spear3xx->average) &
 123                         SPEAR_ADC_DATA_MASK;
 124         }
 125 }
 126
 127 static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate)
 128 {
 129         if (of_device_is_compatible(st->np, "st,spear600-adc")) {
 130                 __raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate),
 131                              &st->adc_base_spear6xx->scan_rate_lo);
 132                 __raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate),
 133                              &st->adc_base_spear6xx->scan_rate_hi);
 134         } else {
 135                 __raw_writel(rate, &st->adc_base_spear3xx->scan_rate);
 136         }
 137 }
 138
 139 static int spear_adc_read_raw(struct iio_dev *indio_dev,
 140                               struct iio_chan_spec const *chan,
 141                               int *val,
 142                               int *val2,
 143                               long mask)
 144 {
 145         struct spear_adc_state *st = iio_priv(indio_dev);
 146         u32 status;
 147
 148         switch (mask) {
 149         case IIO_CHAN_INFO_RAW:
 150                 mutex_lock(&indio_dev->mlock);
 151
 152                 status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) |
 153                         SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) |
 154                         SPEAR_ADC_STATUS_START_CONVERSION |
 155                         SPEAR_ADC_STATUS_ADC_ENABLE;
 156                 if (st->vref_external == 0)
 157                         status |= SPEAR_ADC_STATUS_VREF_INTERNAL;
 158
 159                 spear_adc_set_status(st, status);
 160                 wait_for_completion(&st->completion); /* set by ISR */
 161                 *val = st->value;
 162
 163                 mutex_unlock(&indio_dev->mlock);
 164
 165                 return IIO_VAL_INT;
 166
 167         case IIO_CHAN_INFO_SCALE:
 168                 *val = st->vref_external;
 169                 *val2 = SPEAR_ADC_DATA_BITS;
 170                 return IIO_VAL_FRACTIONAL_LOG2;
 171         case IIO_CHAN_INFO_SAMP_FREQ:
 172                 *val = st->current_clk;
 173                 return IIO_VAL_INT;
 174         }
 175
 176         return -EINVAL;
 177 }
 178
 179 static int spear_adc_write_raw(struct iio_dev *indio_dev,
 180                                struct iio_chan_spec const *chan,
 181                                int val,
 182                                int val2,
 183                                long mask)
 184 {
 185         struct spear_adc_state *st = iio_priv(indio_dev);
 186         int ret = 0;
 187
 188         if (mask != IIO_CHAN_INFO_SAMP_FREQ)
 189                 return -EINVAL;
 190
 191         mutex_lock(&indio_dev->mlock);
 192
 193         if ((val < SPEAR_ADC_CLK_MIN) ||
 194             (val > SPEAR_ADC_CLK_MAX) ||
 195             (val2 != 0)) {
 196                 ret = -EINVAL;
 197                 goto out;
 198         }
 199
 200         spear_adc_set_clk(st, val);
 201
 202 out:
 203         mutex_unlock(&indio_dev->mlock);
 204         return ret;
 205 }
 206
 207 #define SPEAR_ADC_CHAN(idx) {                           \
 208         .type = IIO_VOLTAGE,                            \
 209         .indexed = 1,                                   \
 210         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
 211         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
 212         .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
 213         .channel = idx,                                 \
 214 }
 215
 216 static const struct iio_chan_spec spear_adc_iio_channels[] = {
 217         SPEAR_ADC_CHAN(0),
 218         SPEAR_ADC_CHAN(1),
 219         SPEAR_ADC_CHAN(2),
 220         SPEAR_ADC_CHAN(3),
 221         SPEAR_ADC_CHAN(4),
 222         SPEAR_ADC_CHAN(5),
 223         SPEAR_ADC_CHAN(6),
 224         SPEAR_ADC_CHAN(7),
 225 };
 226
 227 static irqreturn_t spear_adc_isr(int irq, void *dev_id)
 228 {
 229         struct spear_adc_state *st = dev_id;
 230
 231         /* Read value to clear IRQ */
 232         st->value = spear_adc_get_average(st);
 233         complete(&st->completion);
 234
 235         return IRQ_HANDLED;
 236 }
 237
 238 static int spear_adc_configure(struct spear_adc_state *st)
 239 {
 240         int i;
 241
 242         /* Reset ADC core */
 243         spear_adc_set_status(st, 0);
 244         __raw_writel(0, &st->adc_base_spear6xx->clk);
 245         for (i = 0; i < 8; i++)
 246                 spear_adc_set_ctrl(st, i, 0);
 247         spear_adc_set_scanrate(st, 0);
 248
 249         spear_adc_set_clk(st, st->sampling_freq);
 250
 251         return 0;
 252 }
 253
 254 static const struct iio_info spear_adc_info = {
 255         .read_raw = &spear_adc_read_raw,
 256         .write_raw = &spear_adc_write_raw,
 257         .driver_module = THIS_MODULE,
 258 };
 259
 260 static int spear_adc_probe(struct platform_device *pdev)
 261 {
 262         struct device_node *np = pdev->dev.of_node;
 263         struct device *dev = &pdev->dev;
 264         struct spear_adc_state *st;
 265         struct resource *res;
 266         struct iio_dev *indio_dev = NULL;
 267         int ret = -ENODEV;
 268         int irq;
 269
 270         indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state));
 271         if (!indio_dev) {
 272                 dev_err(dev, "failed allocating iio device\n");
 273                 return -ENOMEM;
 274         }
 275
 276         st = iio_priv(indio_dev);
 277         st->np = np;
 278
 279         /*
 280          * SPEAr600 has a different register layout than other SPEAr SoC's
 281          * (e.g. SPEAr3xx). Let's provide two register base addresses
 282          * to support multi-arch kernels.
 283          */
 284         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 285         st->adc_base_spear6xx = devm_ioremap_resource(&pdev->dev, res);
 286         if (IS_ERR(st->adc_base_spear6xx))
 287                 return PTR_ERR(st->adc_base_spear6xx);
 288
 289         st->adc_base_spear3xx =
 290                 (struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx;
 291
 292         st->clk = devm_clk_get(dev, NULL);
 293         if (IS_ERR(st->clk)) {
 294                 dev_err(dev, "failed getting clock\n");
 295                 return PTR_ERR(st->clk);
 296         }
 297
 298         ret = clk_prepare_enable(st->clk);
 299         if (ret) {
 300                 dev_err(dev, "failed enabling clock\n");
 301                 return ret;
 302         }
 303
 304         irq = platform_get_irq(pdev, 0);
 305         if (irq <= 0) {
 306                 dev_err(dev, "failed getting interrupt resource\n");
 307                 ret = -EINVAL;
 308                 goto errout2;
 309         }
 310
 311         ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME,
 312                                st);
 313         if (ret < 0) {
 314                 dev_err(dev, "failed requesting interrupt\n");
 315                 goto errout2;
 316         }
 317
 318         if (of_property_read_u32(np, "sampling-frequency",
 319                                  &st->sampling_freq)) {
 320                 dev_err(dev, "sampling-frequency missing in DT\n");
 321                 ret = -EINVAL;
 322                 goto errout2;
 323         }
 324
 325         /*
 326          * Optional avg_samples defaults to 0, resulting in single data
 327          * conversion
 328          */
 329         of_property_read_u32(np, "average-samples", &st->avg_samples);
 330
 331         /*
 332          * Optional vref_external defaults to 0, resulting in internal vref
 333          * selection
 334          */
 335         of_property_read_u32(np, "vref-external", &st->vref_external);
 336
 337         spear_adc_configure(st);
 338
 339         platform_set_drvdata(pdev, indio_dev);
 340
 341         init_completion(&st->completion);
 342
 343         indio_dev->name = SPEAR_ADC_MOD_NAME;
 344         indio_dev->dev.parent = dev;
 345         indio_dev->info = &spear_adc_info;
 346         indio_dev->modes = INDIO_DIRECT_MODE;
 347         indio_dev->channels = spear_adc_iio_channels;
 348         indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);
 349
 350         ret = iio_device_register(indio_dev);
 351         if (ret)
 352                 goto errout2;
 353
 354         dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);
 355
 356         return 0;
 357
 358 errout2:
 359         clk_disable_unprepare(st->clk);
 360         return ret;
 361 }
 362
 363 static int spear_adc_remove(struct platform_device *pdev)
 364 {
 365         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 366         struct spear_adc_state *st = iio_priv(indio_dev);
 367
 368         iio_device_unregister(indio_dev);
 369         clk_disable_unprepare(st->clk);
 370
 371         return 0;
 372 }
 373
 374 #ifdef CONFIG_OF
 375 static const struct of_device_id spear_adc_dt_ids[] = {
 376         { .compatible = "st,spear600-adc", },
 377         { /* sentinel */ }
 378 };
 379 MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
 380 #endif
 381
 382 static struct platform_driver spear_adc_driver = {
 383         .probe          = spear_adc_probe,
 384         .remove         = spear_adc_remove,
 385         .driver         = {
 386                 .name   = SPEAR_ADC_MOD_NAME,
 387                 .of_match_table = of_match_ptr(spear_adc_dt_ids),
 388         },
 389 };
 390
 391 module_platform_driver(spear_adc_driver);
 392
 393 MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
 394 MODULE_DESCRIPTION("SPEAr ADC driver");
 395 MODULE_LICENSE("GPL");