drivers/i2c/busses/i2c-digicolor.c

   1 /*
   2  * I2C bus driver for Conexant Digicolor SoCs
   3  *
   4  * Author: Baruch Siach <baruch@tkos.co.il>
   5  *
   6  * Copyright (C) 2015 Paradox Innovation Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/completion.h>
  15 #include <linux/delay.h>
  16 #include <linux/i2c.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/io.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/of.h>
  22 #include <linux/platform_device.h>
  23
  24 #define DEFAULT_FREQ            100000
  25 #define TIMEOUT_MS              100
  26
  27 #define II_CONTROL              0x0
  28 #define II_CONTROL_LOCAL_RESET  BIT(0)
  29
  30 #define II_CLOCKTIME            0x1
  31
  32 #define II_COMMAND              0x2
  33 #define II_CMD_START            1
  34 #define II_CMD_RESTART          2
  35 #define II_CMD_SEND_ACK         3
  36 #define II_CMD_GET_ACK          6
  37 #define II_CMD_GET_NOACK        7
  38 #define II_CMD_STOP             10
  39 #define II_COMMAND_GO           BIT(7)
  40 #define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3)
  41 #define II_CMD_STATUS_NORMAL    0
  42 #define II_CMD_STATUS_ACK_GOOD  1
  43 #define II_CMD_STATUS_ACK_BAD   2
  44 #define II_CMD_STATUS_ABORT     3
  45
  46 #define II_DATA                 0x3
  47 #define II_INTFLAG_CLEAR        0x8
  48 #define II_INTENABLE            0xa
  49
  50 struct dc_i2c {
  51         struct i2c_adapter      adap;
  52         struct device           *dev;
  53         void __iomem            *regs;
  54         struct clk              *clk;
  55         unsigned int            frequency;
  56
  57         struct i2c_msg          *msg;
  58         unsigned int            msgbuf_ptr;
  59         int                     last;
  60         spinlock_t              lock;
  61         struct completion       done;
  62         int                     state;
  63         int                     error;
  64 };
  65
  66 enum {
  67         STATE_IDLE,
  68         STATE_START,
  69         STATE_ADDR,
  70         STATE_WRITE,
  71         STATE_READ,
  72         STATE_STOP,
  73 };
  74
  75 static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
  76 {
  77         writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
  78 }
  79
  80 static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
  81 {
  82         u8 addr = (msg->addr & 0x7f) << 1;
  83
  84         if (msg->flags & I2C_M_RD)
  85                 addr |= 1;
  86
  87         return addr;
  88 }
  89
  90 static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
  91 {
  92         writeb_relaxed(data, i2c->regs + II_DATA);
  93 }
  94
  95 static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
  96 {
  97         dc_i2c_data(i2c, byte);
  98         dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
  99 }
 100
 101 static void dc_i2c_write_buf(struct dc_i2c *i2c)
 102 {
 103         dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
 104 }
 105
 106 static void dc_i2c_next_read(struct dc_i2c *i2c)
 107 {
 108         bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);
 109
 110         dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
 111 }
 112
 113 static void dc_i2c_stop(struct dc_i2c *i2c)
 114 {
 115         i2c->state = STATE_STOP;
 116         if (i2c->last)
 117                 dc_i2c_cmd(i2c, II_CMD_STOP);
 118         else
 119                 complete(&i2c->done);
 120 }
 121
 122 static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
 123 {
 124         return readb_relaxed(i2c->regs + II_DATA);
 125 }
 126
 127 static void dc_i2c_read_buf(struct dc_i2c *i2c)
 128 {
 129         i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
 130         dc_i2c_next_read(i2c);
 131 }
 132
 133 static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
 134 {
 135         if (enable)
 136                 writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
 137         writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
 138 }
 139
 140 static int dc_i2c_cmd_status(struct dc_i2c *i2c)
 141 {
 142         u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
 143
 144         return II_COMMAND_COMPLETION_STATUS(cmd);
 145 }
 146
 147 static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
 148 {
 149         struct i2c_msg *msg = i2c->msg;
 150
 151         if (!(msg->flags & I2C_M_NOSTART)) {
 152                 i2c->state = STATE_START;
 153                 dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
 154         } else if (msg->flags & I2C_M_RD) {
 155                 i2c->state = STATE_READ;
 156                 dc_i2c_next_read(i2c);
 157         } else {
 158                 i2c->state = STATE_WRITE;
 159                 dc_i2c_write_buf(i2c);
 160         }
 161 }
 162
 163 static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
 164 {
 165         struct dc_i2c *i2c = dev_id;
 166         int cmd_status = dc_i2c_cmd_status(i2c);
 167         unsigned long flags;
 168         u8 addr_cmd;
 169
 170         writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
 171
 172         spin_lock_irqsave(&i2c->lock, flags);
 173
 174         if (cmd_status == II_CMD_STATUS_ACK_BAD
 175             || cmd_status == II_CMD_STATUS_ABORT) {
 176                 i2c->error = -EIO;
 177                 complete(&i2c->done);
 178                 goto out;
 179         }
 180
 181         switch (i2c->state) {
 182         case STATE_START:
 183                 addr_cmd = dc_i2c_addr_cmd(i2c->msg);
 184                 dc_i2c_write_byte(i2c, addr_cmd);
 185                 i2c->state = STATE_ADDR;
 186                 break;
 187         case STATE_ADDR:
 188                 if (i2c->msg->flags & I2C_M_RD) {
 189                         dc_i2c_next_read(i2c);
 190                         i2c->state = STATE_READ;
 191                         break;
 192                 }
 193                 i2c->state = STATE_WRITE;
 194                 /* fall through */
 195         case STATE_WRITE:
 196                 if (i2c->msgbuf_ptr < i2c->msg->len)
 197                         dc_i2c_write_buf(i2c);
 198                 else
 199                         dc_i2c_stop(i2c);
 200                 break;
 201         case STATE_READ:
 202                 if (i2c->msgbuf_ptr < i2c->msg->len)
 203                         dc_i2c_read_buf(i2c);
 204                 else
 205                         dc_i2c_stop(i2c);
 206                 break;
 207         case STATE_STOP:
 208                 i2c->state = STATE_IDLE;
 209                 complete(&i2c->done);
 210                 break;
 211         }
 212
 213 out:
 214         spin_unlock_irqrestore(&i2c->lock, flags);
 215         return IRQ_HANDLED;
 216 }
 217
 218 static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
 219                            int last)
 220 {
 221         unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS);
 222         unsigned long flags;
 223
 224         spin_lock_irqsave(&i2c->lock, flags);
 225         i2c->msg = msg;
 226         i2c->msgbuf_ptr = 0;
 227         i2c->last = last;
 228         i2c->error = 0;
 229
 230         reinit_completion(&i2c->done);
 231         dc_i2c_set_irq(i2c, 1);
 232         dc_i2c_start_msg(i2c, first);
 233         spin_unlock_irqrestore(&i2c->lock, flags);
 234
 235         timeout = wait_for_completion_timeout(&i2c->done, timeout);
 236         dc_i2c_set_irq(i2c, 0);
 237         if (timeout == 0) {
 238                 i2c->state = STATE_IDLE;
 239                 return -ETIMEDOUT;
 240         }
 241
 242         if (i2c->error)
 243                 return i2c->error;
 244
 245         return 0;
 246 }
 247
 248 static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 249 {
 250         struct dc_i2c *i2c = adap->algo_data;
 251         int i, ret;
 252
 253         for (i = 0; i < num; i++) {
 254                 ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
 255                 if (ret)
 256                         return ret;
 257         }
 258
 259         return num;
 260 }
 261
 262 static int dc_i2c_init_hw(struct dc_i2c *i2c)
 263 {
 264         unsigned long clk_rate = clk_get_rate(i2c->clk);
 265         unsigned int clocktime;
 266
 267         writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
 268         udelay(100);
 269         writeb_relaxed(0, i2c->regs + II_CONTROL);
 270         udelay(100);
 271
 272         clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
 273         if (clocktime < 1 || clocktime > 0xff) {
 274                 dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
 275                         i2c->frequency);
 276                 return -EINVAL;
 277         }
 278         writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);
 279
 280         return 0;
 281 }
 282
 283 static u32 dc_i2c_func(struct i2c_adapter *adap)
 284 {
 285         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
 286 }
 287
 288 static const struct i2c_algorithm dc_i2c_algorithm = {
 289         .master_xfer    = dc_i2c_xfer,
 290         .functionality  = dc_i2c_func,
 291 };
 292
 293 static int dc_i2c_probe(struct platform_device *pdev)
 294 {
 295         struct device_node *np = pdev->dev.of_node;
 296         struct dc_i2c *i2c;
 297         struct resource *r;
 298         int ret = 0, irq;
 299
 300         i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
 301         if (!i2c)
 302                 return -ENOMEM;
 303
 304         if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 305                                  &i2c->frequency))
 306                 i2c->frequency = DEFAULT_FREQ;
 307
 308         i2c->dev = &pdev->dev;
 309         platform_set_drvdata(pdev, i2c);
 310
 311         spin_lock_init(&i2c->lock);
 312         init_completion(&i2c->done);
 313
 314         i2c->clk = devm_clk_get(&pdev->dev, NULL);
 315         if (IS_ERR(i2c->clk))
 316                 return PTR_ERR(i2c->clk);
 317
 318         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 319         i2c->regs = devm_ioremap_resource(&pdev->dev, r);
 320         if (IS_ERR(i2c->regs))
 321                 return PTR_ERR(i2c->regs);
 322
 323         irq = platform_get_irq(pdev, 0);
 324         if (irq < 0)
 325                 return irq;
 326
 327         ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
 328                                dev_name(&pdev->dev), i2c);
 329         if (ret < 0)
 330                 return ret;
 331
 332         strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
 333                 sizeof(i2c->adap.name));
 334         i2c->adap.owner = THIS_MODULE;
 335         i2c->adap.algo = &dc_i2c_algorithm;
 336         i2c->adap.dev.parent = &pdev->dev;
 337         i2c->adap.dev.of_node = np;
 338         i2c->adap.algo_data = i2c;
 339
 340         ret = dc_i2c_init_hw(i2c);
 341         if (ret)
 342                 return ret;
 343
 344         ret = clk_prepare_enable(i2c->clk);
 345         if (ret < 0)
 346                 return ret;
 347
 348         ret = i2c_add_adapter(&i2c->adap);
 349         if (ret < 0) {
 350                 clk_unprepare(i2c->clk);
 351                 return ret;
 352         }
 353
 354         return 0;
 355 }
 356
 357 static int dc_i2c_remove(struct platform_device *pdev)
 358 {
 359         struct dc_i2c *i2c = platform_get_drvdata(pdev);
 360
 361         i2c_del_adapter(&i2c->adap);
 362         clk_disable_unprepare(i2c->clk);
 363
 364         return 0;
 365 }
 366
 367 static const struct of_device_id dc_i2c_match[] = {
 368         { .compatible = "cnxt,cx92755-i2c" },
 369         { },
 370 };
 371 MODULE_DEVICE_TABLE(of, dc_i2c_match);
 372
 373 static struct platform_driver dc_i2c_driver = {
 374         .probe   = dc_i2c_probe,
 375         .remove  = dc_i2c_remove,
 376         .driver  = {
 377                 .name  = "digicolor-i2c",
 378                 .of_match_table = dc_i2c_match,
 379         },
 380 };
 381 module_platform_driver(dc_i2c_driver);
 382
 383 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 384 MODULE_DESCRIPTION("Conexant Digicolor I2C master driver");
 385 MODULE_LICENSE("GPL v2");