drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2016 Maxime Ripard <maxime.ripard@free-electrons.com>
   4  * Copyright (C) 2017 Jonathan Liu <net147@gmail.com>
   5  */
   6
   7 #include <linux/clk.h>
   8 #include <linux/i2c.h>
   9 #include <linux/iopoll.h>
  10
  11 #include "sun4i_hdmi.h"
  12
  13 #define SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK ( \
  14         SUN4I_HDMI_DDC_INT_STATUS_ILLEGAL_FIFO_OPERATION | \
  15         SUN4I_HDMI_DDC_INT_STATUS_DDC_RX_FIFO_UNDERFLOW | \
  16         SUN4I_HDMI_DDC_INT_STATUS_DDC_TX_FIFO_OVERFLOW | \
  17         SUN4I_HDMI_DDC_INT_STATUS_ARBITRATION_ERROR | \
  18         SUN4I_HDMI_DDC_INT_STATUS_ACK_ERROR | \
  19         SUN4I_HDMI_DDC_INT_STATUS_BUS_ERROR \
  20 )
  21
  22 /* FIFO request bit is set when FIFO level is above RX_THRESHOLD during read */
  23 #define RX_THRESHOLD SUN4I_HDMI_DDC_FIFO_CTRL_RX_THRES_MAX
  24
  25 static int fifo_transfer(struct sun4i_hdmi *hdmi, u8 *buf, int len, bool read)
  26 {
  27         /*
  28          * 1 byte takes 9 clock cycles (8 bits + 1 ACK) = 90 us for 100 kHz
  29          * clock. As clock rate is fixed, just round it up to 100 us.
  30          */
  31         const unsigned long byte_time_ns = 100;
  32         const u32 mask = SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK |
  33                          SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST |
  34                          SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE;
  35         u32 reg;
  36         /*
  37          * If threshold is inclusive, then the FIFO may only have
  38          * RX_THRESHOLD number of bytes, instead of RX_THRESHOLD + 1.
  39          */
  40         int read_len = RX_THRESHOLD +
  41                 (hdmi->variant->ddc_fifo_thres_incl ? 0 : 1);
  42
  43         /*
  44          * Limit transfer length by FIFO threshold or FIFO size.
  45          * For TX the threshold is for an empty FIFO.
  46          */
  47         len = min_t(int, len, read ? read_len : SUN4I_HDMI_DDC_FIFO_SIZE);
  48
  49         /* Wait until error, FIFO request bit set or transfer complete */
  50         if (regmap_field_read_poll_timeout(hdmi->field_ddc_int_status, reg,
  51                                            reg & mask, len * byte_time_ns,
  52                                            100000))
  53                 return -ETIMEDOUT;
  54
  55         if (reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK)
  56                 return -EIO;
  57
  58         if (read)
  59                 readsb(hdmi->base + hdmi->variant->ddc_fifo_reg, buf, len);
  60         else
  61                 writesb(hdmi->base + hdmi->variant->ddc_fifo_reg, buf, len);
  62
  63         /* Clear FIFO request bit by forcing a write to that bit */
  64         regmap_field_force_write(hdmi->field_ddc_int_status,
  65                                  SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST);
  66
  67         return len;
  68 }
  69
  70 static int xfer_msg(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
  71 {
  72         int i, len;
  73         u32 reg;
  74
  75         /* Set FIFO direction */
  76         if (hdmi->variant->ddc_fifo_has_dir) {
  77                 reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
  78                 reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
  79                 reg |= (msg->flags & I2C_M_RD) ?
  80                        SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ :
  81                        SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE;
  82                 writel(reg, hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
  83         }
  84
  85         /* Clear address register (not cleared by soft reset) */
  86         regmap_field_write(hdmi->field_ddc_addr_reg, 0);
  87
  88         /* Set I2C address */
  89         regmap_field_write(hdmi->field_ddc_slave_addr, msg->addr);
  90
  91         /*
  92          * Set FIFO RX/TX thresholds and clear FIFO
  93          *
  94          * If threshold is inclusive, we can set the TX threshold to
  95          * 0 instead of 1.
  96          */
  97         regmap_field_write(hdmi->field_ddc_fifo_tx_thres,
  98                            hdmi->variant->ddc_fifo_thres_incl ? 0 : 1);
  99         regmap_field_write(hdmi->field_ddc_fifo_rx_thres, RX_THRESHOLD);
 100         regmap_field_write(hdmi->field_ddc_fifo_clear, 1);
 101         if (regmap_field_read_poll_timeout(hdmi->field_ddc_fifo_clear,
 102                                            reg, !reg, 100, 2000))
 103                 return -EIO;
 104
 105         /* Set transfer length */
 106         regmap_field_write(hdmi->field_ddc_byte_count, msg->len);
 107
 108         /* Set command */
 109         regmap_field_write(hdmi->field_ddc_cmd,
 110                            msg->flags & I2C_M_RD ?
 111                            SUN4I_HDMI_DDC_CMD_IMPLICIT_READ :
 112                            SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE);
 113
 114         /* Clear interrupt status bits by forcing a write */
 115         regmap_field_force_write(hdmi->field_ddc_int_status,
 116                                  SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK |
 117                                  SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST |
 118                                  SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE);
 119
 120         /* Start command */
 121         regmap_field_write(hdmi->field_ddc_start, 1);
 122
 123         /* Transfer bytes */
 124         for (i = 0; i < msg->len; i += len) {
 125                 len = fifo_transfer(hdmi, msg->buf + i, msg->len - i,
 126                                     msg->flags & I2C_M_RD);
 127                 if (len <= 0)
 128                         return len;
 129         }
 130
 131         /* Wait for command to finish */
 132         if (regmap_field_read_poll_timeout(hdmi->field_ddc_start,
 133                                            reg, !reg, 100, 100000))
 134                 return -EIO;
 135
 136         /* Check for errors */
 137         regmap_field_read(hdmi->field_ddc_int_status, &reg);
 138         if ((reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK) ||
 139             !(reg & SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE)) {
 140                 return -EIO;
 141         }
 142
 143         return 0;
 144 }
 145
 146 static int sun4i_hdmi_i2c_xfer(struct i2c_adapter *adap,
 147                                struct i2c_msg *msgs, int num)
 148 {
 149         struct sun4i_hdmi *hdmi = i2c_get_adapdata(adap);
 150         u32 reg;
 151         int err, i, ret = num;
 152
 153         for (i = 0; i < num; i++) {
 154                 if (!msgs[i].len)
 155                         return -EINVAL;
 156                 if (msgs[i].len > SUN4I_HDMI_DDC_BYTE_COUNT_MAX)
 157                         return -EINVAL;
 158         }
 159
 160         /* DDC clock needs to be enabled for the module to work */
 161         clk_prepare_enable(hdmi->ddc_clk);
 162         clk_set_rate(hdmi->ddc_clk, 100000);
 163
 164         /* Reset I2C controller */
 165         regmap_field_write(hdmi->field_ddc_en, 1);
 166         regmap_field_write(hdmi->field_ddc_reset, 1);
 167         if (regmap_field_read_poll_timeout(hdmi->field_ddc_reset,
 168                                            reg, !reg, 100, 2000)) {
 169                 clk_disable_unprepare(hdmi->ddc_clk);
 170                 return -EIO;
 171         }
 172
 173         regmap_field_write(hdmi->field_ddc_sck_en, 1);
 174         regmap_field_write(hdmi->field_ddc_sda_en, 1);
 175
 176         for (i = 0; i < num; i++) {
 177                 err = xfer_msg(hdmi, &msgs[i]);
 178                 if (err) {
 179                         ret = err;
 180                         break;
 181                 }
 182         }
 183
 184         clk_disable_unprepare(hdmi->ddc_clk);
 185         return ret;
 186 }
 187
 188 static u32 sun4i_hdmi_i2c_func(struct i2c_adapter *adap)
 189 {
 190         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 191 }
 192
 193 static const struct i2c_algorithm sun4i_hdmi_i2c_algorithm = {
 194         .master_xfer    = sun4i_hdmi_i2c_xfer,
 195         .functionality  = sun4i_hdmi_i2c_func,
 196 };
 197
 198 static int sun4i_hdmi_init_regmap_fields(struct sun4i_hdmi *hdmi)
 199 {
 200         hdmi->field_ddc_en =
 201                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 202                                         hdmi->variant->field_ddc_en);
 203         if (IS_ERR(hdmi->field_ddc_en))
 204                 return PTR_ERR(hdmi->field_ddc_en);
 205
 206         hdmi->field_ddc_start =
 207                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 208                                         hdmi->variant->field_ddc_start);
 209         if (IS_ERR(hdmi->field_ddc_start))
 210                 return PTR_ERR(hdmi->field_ddc_start);
 211
 212         hdmi->field_ddc_reset =
 213                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 214                                         hdmi->variant->field_ddc_reset);
 215         if (IS_ERR(hdmi->field_ddc_reset))
 216                 return PTR_ERR(hdmi->field_ddc_reset);
 217
 218         hdmi->field_ddc_addr_reg =
 219                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 220                                         hdmi->variant->field_ddc_addr_reg);
 221         if (IS_ERR(hdmi->field_ddc_addr_reg))
 222                 return PTR_ERR(hdmi->field_ddc_addr_reg);
 223
 224         hdmi->field_ddc_slave_addr =
 225                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 226                                         hdmi->variant->field_ddc_slave_addr);
 227         if (IS_ERR(hdmi->field_ddc_slave_addr))
 228                 return PTR_ERR(hdmi->field_ddc_slave_addr);
 229
 230         hdmi->field_ddc_int_mask =
 231                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 232                                         hdmi->variant->field_ddc_int_mask);
 233         if (IS_ERR(hdmi->field_ddc_int_mask))
 234                 return PTR_ERR(hdmi->field_ddc_int_mask);
 235
 236         hdmi->field_ddc_int_status =
 237                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 238                                         hdmi->variant->field_ddc_int_status);
 239         if (IS_ERR(hdmi->field_ddc_int_status))
 240                 return PTR_ERR(hdmi->field_ddc_int_status);
 241
 242         hdmi->field_ddc_fifo_clear =
 243                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 244                                         hdmi->variant->field_ddc_fifo_clear);
 245         if (IS_ERR(hdmi->field_ddc_fifo_clear))
 246                 return PTR_ERR(hdmi->field_ddc_fifo_clear);
 247
 248         hdmi->field_ddc_fifo_rx_thres =
 249                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 250                                         hdmi->variant->field_ddc_fifo_rx_thres);
 251         if (IS_ERR(hdmi->field_ddc_fifo_rx_thres))
 252                 return PTR_ERR(hdmi->field_ddc_fifo_rx_thres);
 253
 254         hdmi->field_ddc_fifo_tx_thres =
 255                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 256                                         hdmi->variant->field_ddc_fifo_tx_thres);
 257         if (IS_ERR(hdmi->field_ddc_fifo_tx_thres))
 258                 return PTR_ERR(hdmi->field_ddc_fifo_tx_thres);
 259
 260         hdmi->field_ddc_byte_count =
 261                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 262                                         hdmi->variant->field_ddc_byte_count);
 263         if (IS_ERR(hdmi->field_ddc_byte_count))
 264                 return PTR_ERR(hdmi->field_ddc_byte_count);
 265
 266         hdmi->field_ddc_cmd =
 267                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 268                                         hdmi->variant->field_ddc_cmd);
 269         if (IS_ERR(hdmi->field_ddc_cmd))
 270                 return PTR_ERR(hdmi->field_ddc_cmd);
 271
 272         hdmi->field_ddc_sda_en =
 273                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 274                                         hdmi->variant->field_ddc_sda_en);
 275         if (IS_ERR(hdmi->field_ddc_sda_en))
 276                 return PTR_ERR(hdmi->field_ddc_sda_en);
 277
 278         hdmi->field_ddc_sck_en =
 279                 devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 280                                         hdmi->variant->field_ddc_sck_en);
 281         if (IS_ERR(hdmi->field_ddc_sck_en))
 282                 return PTR_ERR(hdmi->field_ddc_sck_en);
 283
 284         return 0;
 285 }
 286
 287 int sun4i_hdmi_i2c_create(struct device *dev, struct sun4i_hdmi *hdmi)
 288 {
 289         struct i2c_adapter *adap;
 290         int ret = 0;
 291
 292         ret = sun4i_ddc_create(hdmi, hdmi->ddc_parent_clk);
 293         if (ret)
 294                 return ret;
 295
 296         ret = sun4i_hdmi_init_regmap_fields(hdmi);
 297         if (ret)
 298                 return ret;
 299
 300         adap = devm_kzalloc(dev, sizeof(*adap), GFP_KERNEL);
 301         if (!adap)
 302                 return -ENOMEM;
 303
 304         adap->owner = THIS_MODULE;
 305         adap->class = I2C_CLASS_DDC;
 306         adap->algo = &sun4i_hdmi_i2c_algorithm;
 307         strlcpy(adap->name, "sun4i_hdmi_i2c adapter", sizeof(adap->name));
 308         i2c_set_adapdata(adap, hdmi);
 309
 310         ret = i2c_add_adapter(adap);
 311         if (ret)
 312                 return ret;
 313
 314         hdmi->i2c = adap;
 315
 316         return ret;
 317 }