drivers/iio/adc/aspeed_adc.c

   1 /*
   2  * Aspeed AST2400/2500 ADC
   3  *
   4  * Copyright (C) 2017 Google, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/clk-provider.h>
  14 #include <linux/err.h>
  15 #include <linux/errno.h>
  16 #include <linux/io.h>
  17 #include <linux/module.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/types.h>
  22
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/driver.h>
  25 #include <linux/iopoll.h>
  26
  27 #define ASPEED_RESOLUTION_BITS          10
  28 #define ASPEED_CLOCKS_PER_SAMPLE        12
  29
  30 #define ASPEED_REG_ENGINE_CONTROL       0x00
  31 #define ASPEED_REG_INTERRUPT_CONTROL    0x04
  32 #define ASPEED_REG_VGA_DETECT_CONTROL   0x08
  33 #define ASPEED_REG_CLOCK_CONTROL        0x0C
  34 #define ASPEED_REG_MAX                  0xC0
  35
  36 #define ASPEED_OPERATION_MODE_POWER_DOWN        (0x0 << 1)
  37 #define ASPEED_OPERATION_MODE_STANDBY           (0x1 << 1)
  38 #define ASPEED_OPERATION_MODE_NORMAL            (0x7 << 1)
  39
  40 #define ASPEED_ENGINE_ENABLE            BIT(0)
  41
  42 #define ASPEED_ADC_CTRL_INIT_RDY        BIT(8)
  43
  44 #define ASPEED_ADC_INIT_POLLING_TIME    500
  45 #define ASPEED_ADC_INIT_TIMEOUT         500000
  46
  47 struct aspeed_adc_model_data {
  48         const char *model_name;
  49         unsigned int min_sampling_rate; // Hz
  50         unsigned int max_sampling_rate; // Hz
  51         unsigned int vref_voltage;      // mV
  52         bool wait_init_sequence;
  53 };
  54
  55 struct aspeed_adc_data {
  56         struct device   *dev;
  57         void __iomem    *base;
  58         spinlock_t      clk_lock;
  59         struct clk_hw   *clk_prescaler;
  60         struct clk_hw   *clk_scaler;
  61 };
  62
  63 #define ASPEED_CHAN(_idx, _data_reg_addr) {                     \
  64         .type = IIO_VOLTAGE,                                    \
  65         .indexed = 1,                                           \
  66         .channel = (_idx),                                      \
  67         .address = (_data_reg_addr),                            \
  68         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  69         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
  70                                 BIT(IIO_CHAN_INFO_SAMP_FREQ),   \
  71 }
  72
  73 static const struct iio_chan_spec aspeed_adc_iio_channels[] = {
  74         ASPEED_CHAN(0, 0x10),
  75         ASPEED_CHAN(1, 0x12),
  76         ASPEED_CHAN(2, 0x14),
  77         ASPEED_CHAN(3, 0x16),
  78         ASPEED_CHAN(4, 0x18),
  79         ASPEED_CHAN(5, 0x1A),
  80         ASPEED_CHAN(6, 0x1C),
  81         ASPEED_CHAN(7, 0x1E),
  82         ASPEED_CHAN(8, 0x20),
  83         ASPEED_CHAN(9, 0x22),
  84         ASPEED_CHAN(10, 0x24),
  85         ASPEED_CHAN(11, 0x26),
  86         ASPEED_CHAN(12, 0x28),
  87         ASPEED_CHAN(13, 0x2A),
  88         ASPEED_CHAN(14, 0x2C),
  89         ASPEED_CHAN(15, 0x2E),
  90 };
  91
  92 static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
  93                                struct iio_chan_spec const *chan,
  94                                int *val, int *val2, long mask)
  95 {
  96         struct aspeed_adc_data *data = iio_priv(indio_dev);
  97         const struct aspeed_adc_model_data *model_data =
  98                         of_device_get_match_data(data->dev);
  99
 100         switch (mask) {
 101         case IIO_CHAN_INFO_RAW:
 102                 *val = readw(data->base + chan->address);
 103                 return IIO_VAL_INT;
 104
 105         case IIO_CHAN_INFO_SCALE:
 106                 *val = model_data->vref_voltage;
 107                 *val2 = ASPEED_RESOLUTION_BITS;
 108                 return IIO_VAL_FRACTIONAL_LOG2;
 109
 110         case IIO_CHAN_INFO_SAMP_FREQ:
 111                 *val = clk_get_rate(data->clk_scaler->clk) /
 112                                 ASPEED_CLOCKS_PER_SAMPLE;
 113                 return IIO_VAL_INT;
 114
 115         default:
 116                 return -EINVAL;
 117         }
 118 }
 119
 120 static int aspeed_adc_write_raw(struct iio_dev *indio_dev,
 121                                 struct iio_chan_spec const *chan,
 122                                 int val, int val2, long mask)
 123 {
 124         struct aspeed_adc_data *data = iio_priv(indio_dev);
 125         const struct aspeed_adc_model_data *model_data =
 126                         of_device_get_match_data(data->dev);
 127
 128         switch (mask) {
 129         case IIO_CHAN_INFO_SAMP_FREQ:
 130                 if (val < model_data->min_sampling_rate ||
 131                         val > model_data->max_sampling_rate)
 132                         return -EINVAL;
 133
 134                 clk_set_rate(data->clk_scaler->clk,
 135                                 val * ASPEED_CLOCKS_PER_SAMPLE);
 136                 return 0;
 137
 138         case IIO_CHAN_INFO_SCALE:
 139         case IIO_CHAN_INFO_RAW:
 140                 /*
 141                  * Technically, these could be written but the only reasons
 142                  * for doing so seem better handled in userspace.  EPERM is
 143                  * returned to signal this is a policy choice rather than a
 144                  * hardware limitation.
 145                  */
 146                 return -EPERM;
 147
 148         default:
 149                 return -EINVAL;
 150         }
 151 }
 152
 153 static int aspeed_adc_reg_access(struct iio_dev *indio_dev,
 154                                  unsigned int reg, unsigned int writeval,
 155                                  unsigned int *readval)
 156 {
 157         struct aspeed_adc_data *data = iio_priv(indio_dev);
 158
 159         if (!readval || reg % 4 || reg > ASPEED_REG_MAX)
 160                 return -EINVAL;
 161
 162         *readval = readl(data->base + reg);
 163
 164         return 0;
 165 }
 166
 167 static const struct iio_info aspeed_adc_iio_info = {
 168         .driver_module = THIS_MODULE,
 169         .read_raw = aspeed_adc_read_raw,
 170         .write_raw = aspeed_adc_write_raw,
 171         .debugfs_reg_access = aspeed_adc_reg_access,
 172 };
 173
 174 static int aspeed_adc_probe(struct platform_device *pdev)
 175 {
 176         struct iio_dev *indio_dev;
 177         struct aspeed_adc_data *data;
 178         const struct aspeed_adc_model_data *model_data;
 179         struct resource *res;
 180         const char *clk_parent_name;
 181         int ret;
 182         u32 adc_engine_control_reg_val;
 183
 184         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
 185         if (!indio_dev)
 186                 return -ENOMEM;
 187
 188         data = iio_priv(indio_dev);
 189         data->dev = &pdev->dev;
 190
 191         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 192         data->base = devm_ioremap_resource(&pdev->dev, res);
 193         if (IS_ERR(data->base))
 194                 return PTR_ERR(data->base);
 195
 196         /* Register ADC clock prescaler with source specified by device tree. */
 197         spin_lock_init(&data->clk_lock);
 198         clk_parent_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
 199
 200         data->clk_prescaler = clk_hw_register_divider(
 201                                 &pdev->dev, "prescaler", clk_parent_name, 0,
 202                                 data->base + ASPEED_REG_CLOCK_CONTROL,
 203                                 17, 15, 0, &data->clk_lock);
 204         if (IS_ERR(data->clk_prescaler))
 205                 return PTR_ERR(data->clk_prescaler);
 206
 207         /*
 208          * Register ADC clock scaler downstream from the prescaler. Allow rate
 209          * setting to adjust the prescaler as well.
 210          */
 211         data->clk_scaler = clk_hw_register_divider(
 212                                 &pdev->dev, "scaler", "prescaler",
 213                                 CLK_SET_RATE_PARENT,
 214                                 data->base + ASPEED_REG_CLOCK_CONTROL,
 215                                 0, 10, 0, &data->clk_lock);
 216         if (IS_ERR(data->clk_scaler)) {
 217                 ret = PTR_ERR(data->clk_scaler);
 218                 goto scaler_error;
 219         }
 220
 221         model_data = of_device_get_match_data(&pdev->dev);
 222
 223         if (model_data->wait_init_sequence) {
 224                 /* Enable engine in normal mode. */
 225                 writel(ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE,
 226                        data->base + ASPEED_REG_ENGINE_CONTROL);
 227
 228                 /* Wait for initial sequence complete. */
 229                 ret = readl_poll_timeout(data->base + ASPEED_REG_ENGINE_CONTROL,
 230                                          adc_engine_control_reg_val,
 231                                          adc_engine_control_reg_val &
 232                                          ASPEED_ADC_CTRL_INIT_RDY,
 233                                          ASPEED_ADC_INIT_POLLING_TIME,
 234                                          ASPEED_ADC_INIT_TIMEOUT);
 235                 if (ret)
 236                         goto scaler_error;
 237         }
 238
 239         /* Start all channels in normal mode. */
 240         ret = clk_prepare_enable(data->clk_scaler->clk);
 241         if (ret)
 242                 goto clk_enable_error;
 243
 244         adc_engine_control_reg_val = GENMASK(31, 16) |
 245                 ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE;
 246         writel(adc_engine_control_reg_val,
 247                 data->base + ASPEED_REG_ENGINE_CONTROL);
 248
 249         model_data = of_device_get_match_data(&pdev->dev);
 250         indio_dev->name = model_data->model_name;
 251         indio_dev->dev.parent = &pdev->dev;
 252         indio_dev->info = &aspeed_adc_iio_info;
 253         indio_dev->modes = INDIO_DIRECT_MODE;
 254         indio_dev->channels = aspeed_adc_iio_channels;
 255         indio_dev->num_channels = ARRAY_SIZE(aspeed_adc_iio_channels);
 256
 257         ret = iio_device_register(indio_dev);
 258         if (ret)
 259                 goto iio_register_error;
 260
 261         return 0;
 262
 263 iio_register_error:
 264         writel(ASPEED_OPERATION_MODE_POWER_DOWN,
 265                 data->base + ASPEED_REG_ENGINE_CONTROL);
 266         clk_disable_unprepare(data->clk_scaler->clk);
 267 clk_enable_error:
 268         clk_hw_unregister_divider(data->clk_scaler);
 269
 270 scaler_error:
 271         clk_hw_unregister_divider(data->clk_prescaler);
 272         return ret;
 273 }
 274
 275 static int aspeed_adc_remove(struct platform_device *pdev)
 276 {
 277         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 278         struct aspeed_adc_data *data = iio_priv(indio_dev);
 279
 280         iio_device_unregister(indio_dev);
 281         writel(ASPEED_OPERATION_MODE_POWER_DOWN,
 282                 data->base + ASPEED_REG_ENGINE_CONTROL);
 283         clk_disable_unprepare(data->clk_scaler->clk);
 284         clk_hw_unregister_divider(data->clk_scaler);
 285         clk_hw_unregister_divider(data->clk_prescaler);
 286
 287         return 0;
 288 }
 289
 290 static const struct aspeed_adc_model_data ast2400_model_data = {
 291         .model_name = "ast2400-adc",
 292         .vref_voltage = 2500, // mV
 293         .min_sampling_rate = 10000,
 294         .max_sampling_rate = 500000,
 295 };
 296
 297 static const struct aspeed_adc_model_data ast2500_model_data = {
 298         .model_name = "ast2500-adc",
 299         .vref_voltage = 1800, // mV
 300         .min_sampling_rate = 1,
 301         .max_sampling_rate = 1000000,
 302         .wait_init_sequence = true,
 303 };
 304
 305 static const struct of_device_id aspeed_adc_matches[] = {
 306         { .compatible = "aspeed,ast2400-adc", .data = &ast2400_model_data },
 307         { .compatible = "aspeed,ast2500-adc", .data = &ast2500_model_data },
 308         {},
 309 };
 310 MODULE_DEVICE_TABLE(of, aspeed_adc_matches);
 311
 312 static struct platform_driver aspeed_adc_driver = {
 313         .probe = aspeed_adc_probe,
 314         .remove = aspeed_adc_remove,
 315         .driver = {
 316                 .name = KBUILD_MODNAME,
 317                 .of_match_table = aspeed_adc_matches,
 318         }
 319 };
 320
 321 module_platform_driver(aspeed_adc_driver);
 322
 323 MODULE_AUTHOR("Rick Altherr <raltherr@google.com>");
 324 MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver");
 325 MODULE_LICENSE("GPL");