drivers/iio/adc/sun20i-gpadc-iio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * GPADC driver for sunxi platforms (D1, T113-S3 and R329)
   4  * Copyright (c) 2023 Maksim Kiselev <bigunclemax@gmail.com>
   5  */
   6
   7 #include <linux/bitfield.h>
   8 #include <linux/clk.h>
   9 #include <linux/completion.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/io.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/property.h>
  16 #include <linux/reset.h>
  17
  18 #include <linux/iio/iio.h>
  19
  20 #define SUN20I_GPADC_DRIVER_NAME        "sun20i-gpadc"
  21
  22 /* Register map definition */
  23 #define SUN20I_GPADC_SR                 0x00
  24 #define SUN20I_GPADC_CTRL               0x04
  25 #define SUN20I_GPADC_CS_EN              0x08
  26 #define SUN20I_GPADC_FIFO_INTC          0x0c
  27 #define SUN20I_GPADC_FIFO_INTS          0x10
  28 #define SUN20I_GPADC_FIFO_DATA          0X14
  29 #define SUN20I_GPADC_CB_DATA            0X18
  30 #define SUN20I_GPADC_DATAL_INTC         0x20
  31 #define SUN20I_GPADC_DATAH_INTC         0x24
  32 #define SUN20I_GPADC_DATA_INTC          0x28
  33 #define SUN20I_GPADC_DATAL_INTS         0x30
  34 #define SUN20I_GPADC_DATAH_INTS         0x34
  35 #define SUN20I_GPADC_DATA_INTS          0x38
  36 #define SUN20I_GPADC_CH_CMP_DATA(x)     (0x40 + (x) * 4)
  37 #define SUN20I_GPADC_CH_DATA(x)         (0x80 + (x) * 4)
  38
  39 #define SUN20I_GPADC_CTRL_ADC_AUTOCALI_EN_MASK          BIT(23)
  40 #define SUN20I_GPADC_CTRL_WORK_MODE_MASK                GENMASK(19, 18)
  41 #define SUN20I_GPADC_CTRL_ADC_EN_MASK                   BIT(16)
  42 #define SUN20I_GPADC_CS_EN_ADC_CH(x)                    BIT(x)
  43 #define SUN20I_GPADC_DATA_INTC_CH_DATA_IRQ_EN(x)        BIT(x)
  44
  45 #define SUN20I_GPADC_WORK_MODE_SINGLE                   0
  46
  47 struct sun20i_gpadc_iio {
  48         void __iomem            *regs;
  49         struct completion       completion;
  50         int                     last_channel;
  51         /*
  52          * Lock to protect the device state during a potential concurrent
  53          * read access from userspace. Reading a raw value requires a sequence
  54          * of register writes, then a wait for a completion callback,
  55          * and finally a register read, during which userspace could issue
  56          * another read request. This lock protects a read access from
  57          * ocurring before another one has finished.
  58          */
  59         struct mutex            lock;
  60 };
  61
  62 static int sun20i_gpadc_adc_read(struct sun20i_gpadc_iio *info,
  63                                  struct iio_chan_spec const *chan, int *val)
  64 {
  65         u32 ctrl;
  66         int ret = IIO_VAL_INT;
  67
  68         mutex_lock(&info->lock);
  69
  70         reinit_completion(&info->completion);
  71
  72         if (info->last_channel != chan->channel) {
  73                 info->last_channel = chan->channel;
  74
  75                 /* enable the analog input channel */
  76                 writel(SUN20I_GPADC_CS_EN_ADC_CH(chan->channel),
  77                        info->regs + SUN20I_GPADC_CS_EN);
  78
  79                 /* enable the data irq for input channel */
  80                 writel(SUN20I_GPADC_DATA_INTC_CH_DATA_IRQ_EN(chan->channel),
  81                        info->regs + SUN20I_GPADC_DATA_INTC);
  82         }
  83
  84         /* enable the ADC function */
  85         ctrl = readl(info->regs + SUN20I_GPADC_CTRL);
  86         ctrl |= FIELD_PREP(SUN20I_GPADC_CTRL_ADC_EN_MASK, 1);
  87         writel(ctrl, info->regs + SUN20I_GPADC_CTRL);
  88
  89         /*
  90          * According to the datasheet maximum acquire time(TACQ) can be
  91          * (65535+1)/24Mhz and conversion time(CONV_TIME) is always constant
  92          * and equal to 14/24Mhz, so (TACQ+CONV_TIME) <= 2.73125ms.
  93          * A 10ms delay should be enough to make sure an interrupt occurs in
  94          * normal conditions. If it doesn't occur, then there is a timeout.
  95          */
  96         if (!wait_for_completion_timeout(&info->completion, msecs_to_jiffies(10))) {
  97                 ret = -ETIMEDOUT;
  98                 goto err_unlock;
  99         }
 100
 101         /* read the ADC data */
 102         *val = readl(info->regs + SUN20I_GPADC_CH_DATA(chan->channel));
 103
 104 err_unlock:
 105         mutex_unlock(&info->lock);
 106
 107         return ret;
 108 }
 109
 110 static int sun20i_gpadc_read_raw(struct iio_dev *indio_dev,
 111                                  struct iio_chan_spec const *chan, int *val,
 112                                  int *val2, long mask)
 113 {
 114         struct sun20i_gpadc_iio *info = iio_priv(indio_dev);
 115
 116         switch (mask) {
 117         case IIO_CHAN_INFO_RAW:
 118                 return sun20i_gpadc_adc_read(info, chan, val);
 119         case IIO_CHAN_INFO_SCALE:
 120                 /* value in mv = 1800mV / 4096 raw */
 121                 *val = 1800;
 122                 *val2 = 12;
 123                 return IIO_VAL_FRACTIONAL_LOG2;
 124         default:
 125                 return -EINVAL;
 126         }
 127 }
 128
 129 static irqreturn_t sun20i_gpadc_irq_handler(int irq, void *data)
 130 {
 131         struct sun20i_gpadc_iio *info = data;
 132
 133         /* clear data interrupt status register */
 134         writel(GENMASK(31, 0), info->regs + SUN20I_GPADC_DATA_INTS);
 135
 136         complete(&info->completion);
 137
 138         return IRQ_HANDLED;
 139 }
 140
 141 static const struct iio_info sun20i_gpadc_iio_info = {
 142         .read_raw = sun20i_gpadc_read_raw,
 143 };
 144
 145 static void sun20i_gpadc_reset_assert(void *data)
 146 {
 147         struct reset_control *rst = data;
 148
 149         reset_control_assert(rst);
 150 }
 151
 152 static int sun20i_gpadc_alloc_channels(struct iio_dev *indio_dev,
 153                                        struct device *dev)
 154 {
 155         unsigned int channel;
 156         int num_channels, i, ret;
 157         struct iio_chan_spec *channels;
 158
 159         num_channels = device_get_child_node_count(dev);
 160         if (num_channels == 0)
 161                 return dev_err_probe(dev, -ENODEV, "no channel children\n");
 162
 163         channels = devm_kcalloc(dev, num_channels, sizeof(*channels),
 164                                 GFP_KERNEL);
 165         if (!channels)
 166                 return -ENOMEM;
 167
 168         i = 0;
 169         device_for_each_child_node_scoped(dev, node) {
 170                 ret = fwnode_property_read_u32(node, "reg", &channel);
 171                 if (ret)
 172                         return dev_err_probe(dev, ret, "invalid channel number\n");
 173
 174                 channels[i].type = IIO_VOLTAGE;
 175                 channels[i].indexed = 1;
 176                 channels[i].channel = channel;
 177                 channels[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 178                 channels[i].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
 179
 180                 i++;
 181         }
 182
 183         indio_dev->channels = channels;
 184         indio_dev->num_channels = num_channels;
 185
 186         return 0;
 187 }
 188
 189 static int sun20i_gpadc_probe(struct platform_device *pdev)
 190 {
 191         struct device *dev = &pdev->dev;
 192         struct iio_dev *indio_dev;
 193         struct sun20i_gpadc_iio *info;
 194         struct reset_control *rst;
 195         struct clk *clk;
 196         int irq;
 197         int ret;
 198
 199         indio_dev = devm_iio_device_alloc(dev, sizeof(*info));
 200         if (!indio_dev)
 201                 return -ENOMEM;
 202
 203         info = iio_priv(indio_dev);
 204         info->last_channel = -1;
 205
 206         mutex_init(&info->lock);
 207         init_completion(&info->completion);
 208
 209         ret = sun20i_gpadc_alloc_channels(indio_dev, dev);
 210         if (ret)
 211                 return ret;
 212
 213         indio_dev->info = &sun20i_gpadc_iio_info;
 214         indio_dev->name = SUN20I_GPADC_DRIVER_NAME;
 215
 216         info->regs = devm_platform_ioremap_resource(pdev, 0);
 217         if (IS_ERR(info->regs))
 218                 return PTR_ERR(info->regs);
 219
 220         clk = devm_clk_get_enabled(dev, NULL);
 221         if (IS_ERR(clk))
 222                 return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock\n");
 223
 224         rst = devm_reset_control_get_exclusive(dev, NULL);
 225         if (IS_ERR(rst))
 226                 return dev_err_probe(dev, PTR_ERR(rst), "failed to get reset control\n");
 227
 228         ret = reset_control_deassert(rst);
 229         if (ret)
 230                 return dev_err_probe(dev, ret, "failed to deassert reset\n");
 231
 232         ret = devm_add_action_or_reset(dev, sun20i_gpadc_reset_assert, rst);
 233         if (ret)
 234                 return ret;
 235
 236         irq = platform_get_irq(pdev, 0);
 237         if (irq < 0)
 238                 return irq;
 239
 240         ret = devm_request_irq(dev, irq, sun20i_gpadc_irq_handler, 0,
 241                                dev_name(dev), info);
 242         if (ret)
 243                 return dev_err_probe(dev, ret, "failed requesting irq %d\n", irq);
 244
 245         writel(FIELD_PREP(SUN20I_GPADC_CTRL_ADC_AUTOCALI_EN_MASK, 1) |
 246                FIELD_PREP(SUN20I_GPADC_CTRL_WORK_MODE_MASK, SUN20I_GPADC_WORK_MODE_SINGLE),
 247                info->regs + SUN20I_GPADC_CTRL);
 248
 249         ret = devm_iio_device_register(dev, indio_dev);
 250         if (ret)
 251                 return dev_err_probe(dev, ret, "could not register the device\n");
 252
 253         return 0;
 254 }
 255
 256 static const struct of_device_id sun20i_gpadc_of_id[] = {
 257         { .compatible = "allwinner,sun20i-d1-gpadc" },
 258         { /* sentinel */ }
 259 };
 260 MODULE_DEVICE_TABLE(of, sun20i_gpadc_of_id);
 261
 262 static struct platform_driver sun20i_gpadc_driver = {
 263         .driver = {
 264                 .name = SUN20I_GPADC_DRIVER_NAME,
 265                 .of_match_table = sun20i_gpadc_of_id,
 266         },
 267         .probe = sun20i_gpadc_probe,
 268 };
 269 module_platform_driver(sun20i_gpadc_driver);
 270
 271 MODULE_DESCRIPTION("ADC driver for sunxi platforms");
 272 MODULE_AUTHOR("Maksim Kiselev <bigunclemax@gmail.com>");
 273 MODULE_LICENSE("GPL");