drivers/i2c/busses/i2c-emev2.c

   1 /*
   2  * I2C driver for the Renesas EMEV2 SoC
   3  *
   4  * Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com>
   5  * Copyright 2013 Codethink Ltd.
   6  * Copyright 2010-2015 Renesas Electronics Corporation
   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
  10  * as published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/completion.h>
  15 #include <linux/device.h>
  16 #include <linux/i2c.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/io.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/of_device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/sched.h>
  25
  26 /* I2C Registers */
  27 #define I2C_OFS_IICACT0         0x00    /* start */
  28 #define I2C_OFS_IIC0            0x04    /* shift */
  29 #define I2C_OFS_IICC0           0x08    /* control */
  30 #define I2C_OFS_SVA0            0x0c    /* slave address */
  31 #define I2C_OFS_IICCL0          0x10    /* clock select */
  32 #define I2C_OFS_IICX0           0x14    /* extension */
  33 #define I2C_OFS_IICS0           0x18    /* status */
  34 #define I2C_OFS_IICSE0          0x1c    /* status For emulation */
  35 #define I2C_OFS_IICF0           0x20    /* IIC flag */
  36
  37 /* I2C IICACT0 Masks */
  38 #define I2C_BIT_IICE0           0x0001
  39
  40 /* I2C IICC0 Masks */
  41 #define I2C_BIT_LREL0           0x0040
  42 #define I2C_BIT_WREL0           0x0020
  43 #define I2C_BIT_SPIE0           0x0010
  44 #define I2C_BIT_WTIM0           0x0008
  45 #define I2C_BIT_ACKE0           0x0004
  46 #define I2C_BIT_STT0            0x0002
  47 #define I2C_BIT_SPT0            0x0001
  48
  49 /* I2C IICCL0 Masks */
  50 #define I2C_BIT_SMC0            0x0008
  51 #define I2C_BIT_DFC0            0x0004
  52
  53 /* I2C IICSE0 Masks */
  54 #define I2C_BIT_MSTS0           0x0080
  55 #define I2C_BIT_ALD0            0x0040
  56 #define I2C_BIT_EXC0            0x0020
  57 #define I2C_BIT_COI0            0x0010
  58 #define I2C_BIT_TRC0            0x0008
  59 #define I2C_BIT_ACKD0           0x0004
  60 #define I2C_BIT_STD0            0x0002
  61 #define I2C_BIT_SPD0            0x0001
  62
  63 /* I2C IICF0 Masks */
  64 #define I2C_BIT_STCF            0x0080
  65 #define I2C_BIT_IICBSY          0x0040
  66 #define I2C_BIT_STCEN           0x0002
  67 #define I2C_BIT_IICRSV          0x0001
  68
  69 struct em_i2c_device {
  70         void __iomem *base;
  71         struct i2c_adapter adap;
  72         struct completion msg_done;
  73         struct clk *sclk;
  74 };
  75
  76 static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
  77 {
  78         writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg);
  79 }
  80
  81 static int em_i2c_wait_for_event(struct em_i2c_device *priv)
  82 {
  83         unsigned long time_left;
  84         int status;
  85
  86         reinit_completion(&priv->msg_done);
  87
  88         time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout);
  89
  90         if (!time_left)
  91                 return -ETIMEDOUT;
  92
  93         status = readb(priv->base + I2C_OFS_IICSE0);
  94         return status & I2C_BIT_ALD0 ? -EAGAIN : status;
  95 }
  96
  97 static void em_i2c_stop(struct em_i2c_device *priv)
  98 {
  99         /* Send Stop condition */
 100         em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0);
 101
 102         /* Wait for stop condition */
 103         em_i2c_wait_for_event(priv);
 104 }
 105
 106 static void em_i2c_reset(struct i2c_adapter *adap)
 107 {
 108         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 109         int retr;
 110
 111         /* If I2C active */
 112         if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
 113                 /* Disable I2C operation */
 114                 writeb(0, priv->base + I2C_OFS_IICACT0);
 115
 116                 retr = 1000;
 117                 while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr)
 118                         retr--;
 119                 WARN_ON(retr == 0);
 120         }
 121
 122         /* Transfer mode set */
 123         writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0);
 124
 125         /* Can Issue start without detecting a stop, Reservation disabled. */
 126         writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0);
 127
 128         /* I2C enable, 9 bit interrupt mode */
 129         writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0);
 130
 131         /* Enable I2C operation */
 132         writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0);
 133
 134         retr = 1000;
 135         while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr)
 136                 retr--;
 137         WARN_ON(retr == 0);
 138 }
 139
 140 static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
 141                                 int stop)
 142 {
 143         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 144         int count, status, read = !!(msg->flags & I2C_M_RD);
 145
 146         /* Send start condition */
 147         em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0);
 148         em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0);
 149
 150         /* Send slave address and R/W type */
 151         writeb((msg->addr << 1) | read, priv->base + I2C_OFS_IIC0);
 152
 153         /* Wait for transaction */
 154         status = em_i2c_wait_for_event(priv);
 155         if (status < 0)
 156                 goto out_reset;
 157
 158         /* Received NACK (result of setting slave address and R/W) */
 159         if (!(status & I2C_BIT_ACKD0)) {
 160                 em_i2c_stop(priv);
 161                 goto out;
 162         }
 163
 164         /* Extra setup for read transactions */
 165         if (read) {
 166                 /* 8 bit interrupt mode */
 167                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0);
 168                 em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 169
 170                 /* Wait for transaction */
 171                 status = em_i2c_wait_for_event(priv);
 172                 if (status < 0)
 173                         goto out_reset;
 174         }
 175
 176         /* Send / receive data */
 177         for (count = 0; count < msg->len; count++) {
 178                 if (read) { /* Read transaction */
 179                         msg->buf[count] = readb(priv->base + I2C_OFS_IIC0);
 180                         em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0);
 181
 182                 } else { /* Write transaction */
 183                         /* Received NACK */
 184                         if (!(status & I2C_BIT_ACKD0)) {
 185                                 em_i2c_stop(priv);
 186                                 goto out;
 187                         }
 188
 189                         /* Write data */
 190                         writeb(msg->buf[count], priv->base + I2C_OFS_IIC0);
 191                 }
 192
 193                 /* Wait for R/W transaction */
 194                 status = em_i2c_wait_for_event(priv);
 195                 if (status < 0)
 196                         goto out_reset;
 197         }
 198
 199         if (stop)
 200                 em_i2c_stop(priv);
 201
 202         return count;
 203
 204 out_reset:
 205         em_i2c_reset(adap);
 206 out:
 207         return status < 0 ? status : -ENXIO;
 208 }
 209
 210 static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 211         int num)
 212 {
 213         struct em_i2c_device *priv = i2c_get_adapdata(adap);
 214         int ret, i;
 215
 216         if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
 217                 return -EAGAIN;
 218
 219         for (i = 0; i < num; i++) {
 220                 ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
 221                 if (ret < 0)
 222                         return ret;
 223         }
 224
 225         /* I2C transfer completed */
 226         return num;
 227 }
 228
 229 static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
 230 {
 231         struct em_i2c_device *priv = dev_id;
 232
 233         complete(&priv->msg_done);
 234         return IRQ_HANDLED;
 235 }
 236
 237 static u32 em_i2c_func(struct i2c_adapter *adap)
 238 {
 239         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 240 }
 241
 242 static struct i2c_algorithm em_i2c_algo = {
 243         .master_xfer = em_i2c_xfer,
 244         .functionality = em_i2c_func,
 245 };
 246
 247 static int em_i2c_probe(struct platform_device *pdev)
 248 {
 249         struct em_i2c_device *priv;
 250         struct resource *r;
 251         int irq, ret;
 252
 253         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 254         if (!priv)
 255                 return -ENOMEM;
 256
 257         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 258         priv->base = devm_ioremap_resource(&pdev->dev, r);
 259         if (IS_ERR(priv->base))
 260                 return PTR_ERR(priv->base);
 261
 262         strlcpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name));
 263
 264         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
 265         if (IS_ERR(priv->sclk))
 266                 return PTR_ERR(priv->sclk);
 267
 268         clk_prepare_enable(priv->sclk);
 269
 270         priv->adap.timeout = msecs_to_jiffies(100);
 271         priv->adap.retries = 5;
 272         priv->adap.dev.parent = &pdev->dev;
 273         priv->adap.algo = &em_i2c_algo;
 274         priv->adap.owner = THIS_MODULE;
 275         priv->adap.dev.of_node = pdev->dev.of_node;
 276
 277         init_completion(&priv->msg_done);
 278
 279         platform_set_drvdata(pdev, priv);
 280         i2c_set_adapdata(&priv->adap, priv);
 281
 282         em_i2c_reset(&priv->adap);
 283
 284         irq = platform_get_irq(pdev, 0);
 285         ret = devm_request_irq(&pdev->dev, irq, em_i2c_irq_handler, 0,
 286                                 "em_i2c", priv);
 287         if (ret)
 288                 goto err_clk;
 289
 290         ret = i2c_add_adapter(&priv->adap);
 291
 292         if (ret)
 293                 goto err_clk;
 294
 295         dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr, irq);
 296
 297         return 0;
 298
 299 err_clk:
 300         clk_disable_unprepare(priv->sclk);
 301         return ret;
 302 }
 303
 304 static int em_i2c_remove(struct platform_device *dev)
 305 {
 306         struct em_i2c_device *priv = platform_get_drvdata(dev);
 307
 308         i2c_del_adapter(&priv->adap);
 309         clk_disable_unprepare(priv->sclk);
 310
 311         return 0;
 312 }
 313
 314 static const struct of_device_id em_i2c_ids[] = {
 315         { .compatible = "renesas,iic-emev2", },
 316         { }
 317 };
 318
 319 static struct platform_driver em_i2c_driver = {
 320         .probe = em_i2c_probe,
 321         .remove = em_i2c_remove,
 322         .driver = {
 323                 .name = "em-i2c",
 324                 .of_match_table = em_i2c_ids,
 325         }
 326 };
 327 module_platform_driver(em_i2c_driver);
 328
 329 MODULE_DESCRIPTION("EMEV2 I2C bus driver");
 330 MODULE_AUTHOR("Ian Molton and Wolfram Sang <wsa@sang-engineering.com>");
 331 MODULE_LICENSE("GPL v2");
 332 MODULE_DEVICE_TABLE(of, em_i2c_ids);