drivers/i2c/busses/i2c-digicolor.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * I2C bus driver for Conexant Digicolor SoCs
   4  *
   5  * Author: Baruch Siach <baruch@tkos.co.il>
   6  *
   7  * Copyright (C) 2015 Paradox Innovation Ltd.
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/completion.h>
  12 #include <linux/delay.h>
  13 #include <linux/i2c.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/io.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20
  21 #define TIMEOUT_MS              100
  22
  23 #define II_CONTROL              0x0
  24 #define II_CONTROL_LOCAL_RESET  BIT(0)
  25
  26 #define II_CLOCKTIME            0x1
  27
  28 #define II_COMMAND              0x2
  29 #define II_CMD_START            1
  30 #define II_CMD_RESTART          2
  31 #define II_CMD_SEND_ACK         3
  32 #define II_CMD_GET_ACK          6
  33 #define II_CMD_GET_NOACK        7
  34 #define II_CMD_STOP             10
  35 #define II_COMMAND_GO           BIT(7)
  36 #define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3)
  37 #define II_CMD_STATUS_NORMAL    0
  38 #define II_CMD_STATUS_ACK_GOOD  1
  39 #define II_CMD_STATUS_ACK_BAD   2
  40 #define II_CMD_STATUS_ABORT     3
  41
  42 #define II_DATA                 0x3
  43 #define II_INTFLAG_CLEAR        0x8
  44 #define II_INTENABLE            0xa
  45
  46 struct dc_i2c {
  47         struct i2c_adapter      adap;
  48         struct device           *dev;
  49         void __iomem            *regs;
  50         struct clk              *clk;
  51         unsigned int            frequency;
  52
  53         struct i2c_msg          *msg;
  54         unsigned int            msgbuf_ptr;
  55         int                     last;
  56         spinlock_t              lock;
  57         struct completion       done;
  58         int                     state;
  59         int                     error;
  60 };
  61
  62 enum {
  63         STATE_IDLE,
  64         STATE_START,
  65         STATE_ADDR,
  66         STATE_WRITE,
  67         STATE_READ,
  68         STATE_STOP,
  69 };
  70
  71 static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
  72 {
  73         writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
  74 }
  75
  76 static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
  77 {
  78         u8 addr = (msg->addr & 0x7f) << 1;
  79
  80         if (msg->flags & I2C_M_RD)
  81                 addr |= 1;
  82
  83         return addr;
  84 }
  85
  86 static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
  87 {
  88         writeb_relaxed(data, i2c->regs + II_DATA);
  89 }
  90
  91 static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
  92 {
  93         dc_i2c_data(i2c, byte);
  94         dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
  95 }
  96
  97 static void dc_i2c_write_buf(struct dc_i2c *i2c)
  98 {
  99         dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
 100 }
 101
 102 static void dc_i2c_next_read(struct dc_i2c *i2c)
 103 {
 104         bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);
 105
 106         dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
 107 }
 108
 109 static void dc_i2c_stop(struct dc_i2c *i2c)
 110 {
 111         i2c->state = STATE_STOP;
 112         if (i2c->last)
 113                 dc_i2c_cmd(i2c, II_CMD_STOP);
 114         else
 115                 complete(&i2c->done);
 116 }
 117
 118 static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
 119 {
 120         return readb_relaxed(i2c->regs + II_DATA);
 121 }
 122
 123 static void dc_i2c_read_buf(struct dc_i2c *i2c)
 124 {
 125         i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
 126         dc_i2c_next_read(i2c);
 127 }
 128
 129 static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
 130 {
 131         if (enable)
 132                 writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
 133         writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
 134 }
 135
 136 static int dc_i2c_cmd_status(struct dc_i2c *i2c)
 137 {
 138         u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
 139
 140         return II_COMMAND_COMPLETION_STATUS(cmd);
 141 }
 142
 143 static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
 144 {
 145         struct i2c_msg *msg = i2c->msg;
 146
 147         if (!(msg->flags & I2C_M_NOSTART)) {
 148                 i2c->state = STATE_START;
 149                 dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
 150         } else if (msg->flags & I2C_M_RD) {
 151                 i2c->state = STATE_READ;
 152                 dc_i2c_next_read(i2c);
 153         } else {
 154                 i2c->state = STATE_WRITE;
 155                 dc_i2c_write_buf(i2c);
 156         }
 157 }
 158
 159 static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
 160 {
 161         struct dc_i2c *i2c = dev_id;
 162         int cmd_status = dc_i2c_cmd_status(i2c);
 163         u8 addr_cmd;
 164
 165         writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
 166
 167         spin_lock(&i2c->lock);
 168
 169         if (cmd_status == II_CMD_STATUS_ACK_BAD
 170             || cmd_status == II_CMD_STATUS_ABORT) {
 171                 i2c->error = -EIO;
 172                 complete(&i2c->done);
 173                 goto out;
 174         }
 175
 176         switch (i2c->state) {
 177         case STATE_START:
 178                 addr_cmd = dc_i2c_addr_cmd(i2c->msg);
 179                 dc_i2c_write_byte(i2c, addr_cmd);
 180                 i2c->state = STATE_ADDR;
 181                 break;
 182         case STATE_ADDR:
 183                 if (i2c->msg->flags & I2C_M_RD) {
 184                         dc_i2c_next_read(i2c);
 185                         i2c->state = STATE_READ;
 186                         break;
 187                 }
 188                 i2c->state = STATE_WRITE;
 189                 fallthrough;
 190         case STATE_WRITE:
 191                 if (i2c->msgbuf_ptr < i2c->msg->len)
 192                         dc_i2c_write_buf(i2c);
 193                 else
 194                         dc_i2c_stop(i2c);
 195                 break;
 196         case STATE_READ:
 197                 if (i2c->msgbuf_ptr < i2c->msg->len)
 198                         dc_i2c_read_buf(i2c);
 199                 else
 200                         dc_i2c_stop(i2c);
 201                 break;
 202         case STATE_STOP:
 203                 i2c->state = STATE_IDLE;
 204                 complete(&i2c->done);
 205                 break;
 206         }
 207
 208 out:
 209         spin_unlock(&i2c->lock);
 210         return IRQ_HANDLED;
 211 }
 212
 213 static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
 214                            int last)
 215 {
 216         unsigned long time_left = msecs_to_jiffies(TIMEOUT_MS);
 217         unsigned long flags;
 218
 219         spin_lock_irqsave(&i2c->lock, flags);
 220         i2c->msg = msg;
 221         i2c->msgbuf_ptr = 0;
 222         i2c->last = last;
 223         i2c->error = 0;
 224
 225         reinit_completion(&i2c->done);
 226         dc_i2c_set_irq(i2c, 1);
 227         dc_i2c_start_msg(i2c, first);
 228         spin_unlock_irqrestore(&i2c->lock, flags);
 229
 230         time_left = wait_for_completion_timeout(&i2c->done, time_left);
 231         dc_i2c_set_irq(i2c, 0);
 232         if (time_left == 0) {
 233                 i2c->state = STATE_IDLE;
 234                 return -ETIMEDOUT;
 235         }
 236
 237         if (i2c->error)
 238                 return i2c->error;
 239
 240         return 0;
 241 }
 242
 243 static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 244 {
 245         struct dc_i2c *i2c = adap->algo_data;
 246         int i, ret;
 247
 248         for (i = 0; i < num; i++) {
 249                 ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
 250                 if (ret)
 251                         return ret;
 252         }
 253
 254         return num;
 255 }
 256
 257 static int dc_i2c_init_hw(struct dc_i2c *i2c)
 258 {
 259         unsigned long clk_rate = clk_get_rate(i2c->clk);
 260         unsigned int clocktime;
 261
 262         writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
 263         udelay(100);
 264         writeb_relaxed(0, i2c->regs + II_CONTROL);
 265         udelay(100);
 266
 267         clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
 268         if (clocktime < 1 || clocktime > 0xff) {
 269                 dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
 270                         i2c->frequency);
 271                 return -EINVAL;
 272         }
 273         writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);
 274
 275         return 0;
 276 }
 277
 278 static u32 dc_i2c_func(struct i2c_adapter *adap)
 279 {
 280         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
 281 }
 282
 283 static const struct i2c_algorithm dc_i2c_algorithm = {
 284         .xfer = dc_i2c_xfer,
 285         .functionality = dc_i2c_func,
 286 };
 287
 288 static int dc_i2c_probe(struct platform_device *pdev)
 289 {
 290         struct device_node *np = pdev->dev.of_node;
 291         struct dc_i2c *i2c;
 292         int ret = 0, irq;
 293
 294         i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
 295         if (!i2c)
 296                 return -ENOMEM;
 297
 298         if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 299                                  &i2c->frequency))
 300                 i2c->frequency = I2C_MAX_STANDARD_MODE_FREQ;
 301
 302         i2c->dev = &pdev->dev;
 303         platform_set_drvdata(pdev, i2c);
 304
 305         spin_lock_init(&i2c->lock);
 306         init_completion(&i2c->done);
 307
 308         i2c->clk = devm_clk_get(&pdev->dev, NULL);
 309         if (IS_ERR(i2c->clk))
 310                 return PTR_ERR(i2c->clk);
 311
 312         i2c->regs = devm_platform_ioremap_resource(pdev, 0);
 313         if (IS_ERR(i2c->regs))
 314                 return PTR_ERR(i2c->regs);
 315
 316         irq = platform_get_irq(pdev, 0);
 317         if (irq < 0)
 318                 return irq;
 319
 320         ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
 321                                dev_name(&pdev->dev), i2c);
 322         if (ret < 0)
 323                 return ret;
 324
 325         strscpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
 326                 sizeof(i2c->adap.name));
 327         i2c->adap.owner = THIS_MODULE;
 328         i2c->adap.algo = &dc_i2c_algorithm;
 329         i2c->adap.dev.parent = &pdev->dev;
 330         i2c->adap.dev.of_node = np;
 331         i2c->adap.algo_data = i2c;
 332
 333         ret = dc_i2c_init_hw(i2c);
 334         if (ret)
 335                 return ret;
 336
 337         ret = clk_prepare_enable(i2c->clk);
 338         if (ret < 0)
 339                 return ret;
 340
 341         ret = i2c_add_adapter(&i2c->adap);
 342         if (ret < 0) {
 343                 clk_disable_unprepare(i2c->clk);
 344                 return ret;
 345         }
 346
 347         return 0;
 348 }
 349
 350 static void dc_i2c_remove(struct platform_device *pdev)
 351 {
 352         struct dc_i2c *i2c = platform_get_drvdata(pdev);
 353
 354         i2c_del_adapter(&i2c->adap);
 355         clk_disable_unprepare(i2c->clk);
 356 }
 357
 358 static const struct of_device_id dc_i2c_match[] = {
 359         { .compatible = "cnxt,cx92755-i2c" },
 360         { }
 361 };
 362 MODULE_DEVICE_TABLE(of, dc_i2c_match);
 363
 364 static struct platform_driver dc_i2c_driver = {
 365         .probe   = dc_i2c_probe,
 366         .remove = dc_i2c_remove,
 367         .driver  = {
 368                 .name  = "digicolor-i2c",
 369                 .of_match_table = dc_i2c_match,
 370         },
 371 };
 372 module_platform_driver(dc_i2c_driver);
 373
 374 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 375 MODULE_DESCRIPTION("Conexant Digicolor I2C controller driver");
 376 MODULE_LICENSE("GPL v2");