drivers/iio/adc/sophgo-cv1800b-adc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Sophgo CV1800B SARADC Driver
   4  *
   5  *  Copyright (C) Bootlin 2024
   6  *  Author: Thomas Bonnefille <thomas.bonnefille@bootlin.com>
   7  */
   8
   9 #include <linux/array_size.h>
  10 #include <linux/bitfield.h>
  11 #include <linux/bits.h>
  12 #include <linux/cleanup.h>
  13 #include <linux/clk.h>
  14 #include <linux/completion.h>
  15 #include <linux/err.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/iopoll.h>
  18 #include <linux/mod_devicetable.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/types.h>
  23
  24 #include <linux/iio/iio.h>
  25
  26 #define CV1800B_ADC_CTRL_REG                            0x04
  27 #define   CV1800B_ADC_EN                                BIT(0)
  28 #define   CV1800B_ADC_SEL(x)                            BIT((x) + 5)
  29 #define CV1800B_ADC_STATUS_REG                          0x08
  30 #define   CV1800B_ADC_BUSY                              BIT(0)
  31 #define CV1800B_ADC_CYC_SET_REG                         0x0C
  32 #define   CV1800B_MASK_STARTUP_CYCLE                    GENMASK(4, 0)
  33 #define   CV1800B_MASK_SAMPLE_WINDOW                    GENMASK(11, 8)
  34 #define   CV1800B_MASK_CLKDIV                           GENMASK(15, 12)
  35 #define   CV1800B_MASK_COMPARE_CYCLE                    GENMASK(19, 16)
  36 #define CV1800B_ADC_CH_RESULT_REG(x)                    (0x14 + 4 * (x))
  37 #define   CV1800B_ADC_CH_RESULT                         GENMASK(11, 0)
  38 #define   CV1800B_ADC_CH_VALID                          BIT(15)
  39 #define CV1800B_ADC_INTR_EN_REG                         0x20
  40 #define CV1800B_ADC_INTR_CLR_REG                        0x24
  41 #define   CV1800B_ADC_INTR_CLR_BIT                      BIT(0)
  42 #define CV1800B_ADC_INTR_STA_REG                        0x28
  43 #define   CV1800B_ADC_INTR_STA_BIT                      BIT(0)
  44 #define CV1800B_READ_TIMEOUT_MS                         1000
  45 #define CV1800B_READ_TIMEOUT_US                         (CV1800B_READ_TIMEOUT_MS * 1000)
  46
  47 #define CV1800B_ADC_CHANNEL(index)                                      \
  48         {                                                               \
  49                 .type = IIO_VOLTAGE,                                    \
  50                 .indexed = 1,                                           \
  51                 .channel = index,                                       \
  52                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  53                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  54                 .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
  55                 .scan_index = index,                                    \
  56         }
  57
  58 struct cv1800b_adc {
  59         struct completion completion;
  60         void __iomem *regs;
  61         struct mutex lock; /* ADC Control and Result register */
  62         struct clk *clk;
  63         int irq;
  64 };
  65
  66 static const struct iio_chan_spec sophgo_channels[] = {
  67         CV1800B_ADC_CHANNEL(0),
  68         CV1800B_ADC_CHANNEL(1),
  69         CV1800B_ADC_CHANNEL(2),
  70 };
  71
  72 static void cv1800b_adc_start_measurement(struct cv1800b_adc *saradc,
  73                                           int channel)
  74 {
  75         writel(0, saradc->regs + CV1800B_ADC_CTRL_REG);
  76         writel(CV1800B_ADC_SEL(channel) | CV1800B_ADC_EN,
  77                saradc->regs + CV1800B_ADC_CTRL_REG);
  78 }
  79
  80 static int cv1800b_adc_wait(struct cv1800b_adc *saradc)
  81 {
  82         if (saradc->irq < 0) {
  83                 u32 reg;
  84
  85                 return readl_poll_timeout(saradc->regs + CV1800B_ADC_STATUS_REG,
  86                                           reg, !(reg & CV1800B_ADC_BUSY),
  87                                           500, CV1800B_READ_TIMEOUT_US);
  88         }
  89
  90         return wait_for_completion_timeout(&saradc->completion,
  91                                            msecs_to_jiffies(CV1800B_READ_TIMEOUT_MS)) > 0 ?
  92                                            0 : -ETIMEDOUT;
  93 }
  94
  95 static int cv1800b_adc_read_raw(struct iio_dev *indio_dev,
  96                                 struct iio_chan_spec const *chan,
  97                                 int *val, int *val2, long mask)
  98 {
  99         struct cv1800b_adc *saradc = iio_priv(indio_dev);
 100
 101         switch (mask) {
 102         case IIO_CHAN_INFO_RAW: {
 103                 u32 sample;
 104
 105                 scoped_guard(mutex, &saradc->lock) {
 106                         int ret;
 107
 108                         cv1800b_adc_start_measurement(saradc, chan->scan_index);
 109                         ret = cv1800b_adc_wait(saradc);
 110                         if (ret < 0)
 111                                 return ret;
 112
 113                         sample = readl(saradc->regs + CV1800B_ADC_CH_RESULT_REG(chan->scan_index));
 114                 }
 115                 if (!(sample & CV1800B_ADC_CH_VALID))
 116                         return -ENODATA;
 117
 118                 *val = sample & CV1800B_ADC_CH_RESULT;
 119                 return IIO_VAL_INT;
 120         }
 121         case IIO_CHAN_INFO_SCALE:
 122                 *val = 3300;
 123                 *val2 = 12;
 124                 return IIO_VAL_FRACTIONAL_LOG2;
 125         case IIO_CHAN_INFO_SAMP_FREQ: {
 126                 u32 status_reg = readl(saradc->regs + CV1800B_ADC_CYC_SET_REG);
 127                 unsigned int clk_div = (1 + FIELD_GET(CV1800B_MASK_CLKDIV, status_reg));
 128                 unsigned int freq = clk_get_rate(saradc->clk) / clk_div;
 129                 unsigned int nb_startup_cycle = 1 + FIELD_GET(CV1800B_MASK_STARTUP_CYCLE, status_reg);
 130                 unsigned int nb_sample_cycle = 1 + FIELD_GET(CV1800B_MASK_SAMPLE_WINDOW, status_reg);
 131                 unsigned int nb_compare_cycle = 1 + FIELD_GET(CV1800B_MASK_COMPARE_CYCLE, status_reg);
 132
 133                 *val = freq / (nb_startup_cycle + nb_sample_cycle + nb_compare_cycle);
 134                 return IIO_VAL_INT;
 135         }
 136         default:
 137                 return -EINVAL;
 138         }
 139 }
 140
 141 static irqreturn_t cv1800b_adc_interrupt_handler(int irq, void *private)
 142 {
 143         struct cv1800b_adc *saradc = private;
 144         u32 reg = readl(saradc->regs + CV1800B_ADC_INTR_STA_REG);
 145
 146         if (!(FIELD_GET(CV1800B_ADC_INTR_STA_BIT, reg)))
 147                 return IRQ_NONE;
 148
 149         writel(CV1800B_ADC_INTR_CLR_BIT, saradc->regs + CV1800B_ADC_INTR_CLR_REG);
 150         complete(&saradc->completion);
 151
 152         return IRQ_HANDLED;
 153 }
 154
 155 static const struct iio_info cv1800b_adc_info = {
 156         .read_raw = &cv1800b_adc_read_raw,
 157 };
 158
 159 static int cv1800b_adc_probe(struct platform_device *pdev)
 160 {
 161         struct device *dev = &pdev->dev;
 162         struct cv1800b_adc *saradc;
 163         struct iio_dev *indio_dev;
 164         int ret;
 165
 166         indio_dev = devm_iio_device_alloc(dev, sizeof(*saradc));
 167         if (!indio_dev)
 168                 return -ENOMEM;
 169
 170         saradc = iio_priv(indio_dev);
 171         indio_dev->name = "sophgo-cv1800b-adc";
 172         indio_dev->modes = INDIO_DIRECT_MODE;
 173         indio_dev->info = &cv1800b_adc_info;
 174         indio_dev->num_channels = ARRAY_SIZE(sophgo_channels);
 175         indio_dev->channels = sophgo_channels;
 176
 177         saradc->clk = devm_clk_get_enabled(dev, NULL);
 178         if (IS_ERR(saradc->clk))
 179                 return PTR_ERR(saradc->clk);
 180
 181         saradc->regs = devm_platform_ioremap_resource(pdev, 0);
 182         if (IS_ERR(saradc->regs))
 183                 return PTR_ERR(saradc->regs);
 184
 185         saradc->irq = platform_get_irq_optional(pdev, 0);
 186         if (saradc->irq > 0) {
 187                 init_completion(&saradc->completion);
 188                 ret = devm_request_irq(dev, saradc->irq,
 189                                        cv1800b_adc_interrupt_handler, 0,
 190                                        dev_name(dev), saradc);
 191                 if (ret)
 192                         return ret;
 193
 194                 writel(1, saradc->regs + CV1800B_ADC_INTR_EN_REG);
 195         }
 196
 197         ret = devm_mutex_init(dev, &saradc->lock);
 198         if (ret)
 199                 return ret;
 200
 201         writel(FIELD_PREP(CV1800B_MASK_STARTUP_CYCLE, 15) |
 202                FIELD_PREP(CV1800B_MASK_SAMPLE_WINDOW, 15) |
 203                FIELD_PREP(CV1800B_MASK_CLKDIV, 1) |
 204                FIELD_PREP(CV1800B_MASK_COMPARE_CYCLE, 15),
 205                saradc->regs + CV1800B_ADC_CYC_SET_REG);
 206
 207         return devm_iio_device_register(dev, indio_dev);
 208 }
 209
 210 static const struct of_device_id cv1800b_adc_match[] = {
 211         { .compatible = "sophgo,cv1800b-saradc", },
 212         { }
 213 };
 214 MODULE_DEVICE_TABLE(of, cv1800b_adc_match);
 215
 216 static struct platform_driver cv1800b_adc_driver = {
 217         .driver = {
 218                 .name           = "sophgo-cv1800b-saradc",
 219                 .of_match_table = cv1800b_adc_match,
 220         },
 221         .probe = cv1800b_adc_probe,
 222 };
 223 module_platform_driver(cv1800b_adc_driver);
 224
 225 MODULE_AUTHOR("Thomas Bonnefille <thomas.bonnefille@bootlin.com>");
 226 MODULE_DESCRIPTION("Sophgo CV1800B SARADC driver");
 227 MODULE_LICENSE("GPL");