drivers/video/mb862xx/mb862xx-i2c.c

   1 /*
   2  * Coral-P(A)/Lime I2C adapter driver
   3  *
   4  * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/fb.h>
  13 #include <linux/i2c.h>
  14 #include <linux/io.h>
  15 #include <linux/delay.h>
  16
  17 #include "mb862xxfb.h"
  18 #include "mb862xx_reg.h"
  19
  20 static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
  21 {
  22         struct mb862xxfb_par *par = adap->algo_data;
  23         u32 reg;
  24
  25         do {
  26                 udelay(1);
  27                 reg = inreg(i2c, GC_I2C_BCR);
  28                 if (reg & (I2C_INT | I2C_BER))
  29                         break;
  30         } while (1);
  31
  32         return (reg & I2C_BER) ? 0 : 1;
  33 }
  34
  35 static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
  36 {
  37         struct mb862xxfb_par *par = adap->algo_data;
  38
  39         outreg(i2c, GC_I2C_DAR, addr);
  40         outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
  41         outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
  42         if (!mb862xx_i2c_wait_event(adap))
  43                 return -EIO;
  44         par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
  45         return par->i2c_rs;
  46 }
  47
  48 static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
  49 {
  50         struct mb862xxfb_par *par = adap->algo_data;
  51
  52         outreg(i2c, GC_I2C_DAR, byte);
  53         outreg(i2c, GC_I2C_BCR, I2C_START);
  54         if (!mb862xx_i2c_wait_event(adap))
  55                 return -EIO;
  56         return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
  57 }
  58
  59 static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
  60 {
  61         struct mb862xxfb_par *par = adap->algo_data;
  62
  63         outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
  64         if (!mb862xx_i2c_wait_event(adap))
  65                 return 0;
  66         *byte = inreg(i2c, GC_I2C_DAR);
  67         return 1;
  68 }
  69
  70 void mb862xx_i2c_stop(struct i2c_adapter *adap)
  71 {
  72         struct mb862xxfb_par *par = adap->algo_data;
  73
  74         outreg(i2c, GC_I2C_BCR, I2C_STOP);
  75         outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
  76         par->i2c_rs = 0;
  77 }
  78
  79 static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
  80 {
  81         int i, ret = 0;
  82         int last = m->len - 1;
  83
  84         for (i = 0; i < m->len; i++) {
  85                 if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
  86                         ret = -EIO;
  87                         break;
  88                 }
  89         }
  90         return ret;
  91 }
  92
  93 static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
  94 {
  95         int i, ret = 0;
  96
  97         for (i = 0; i < m->len; i++) {
  98                 if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
  99                         ret = -EIO;
 100                         break;
 101                 }
 102         }
 103         return ret;
 104 }
 105
 106 static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 107                         int num)
 108 {
 109         struct mb862xxfb_par *par = adap->algo_data;
 110         struct i2c_msg *m;
 111         int addr;
 112         int i = 0, err = 0;
 113
 114         dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);
 115
 116         for (i = 0; i < num; i++) {
 117                 m = &msgs[i];
 118                 if (!m->len) {
 119                         dev_dbg(par->dev, "%s: null msgs\n", __func__);
 120                         continue;
 121                 }
 122                 addr = m->addr;
 123                 if (m->flags & I2C_M_RD)
 124                         addr |= 1;
 125
 126                 err = mb862xx_i2c_do_address(adap, addr);
 127                 if (err < 0)
 128                         break;
 129                 if (m->flags & I2C_M_RD)
 130                         err = mb862xx_i2c_read(adap, m);
 131                 else
 132                         err = mb862xx_i2c_write(adap, m);
 133         }
 134
 135         if (i)
 136                 mb862xx_i2c_stop(adap);
 137
 138         return (err < 0) ? err : i;
 139 }
 140
 141 static u32 mb862xx_func(struct i2c_adapter *adap)
 142 {
 143         return I2C_FUNC_SMBUS_BYTE_DATA;
 144 }
 145
 146 static const struct i2c_algorithm mb862xx_algo = {
 147         .master_xfer    = mb862xx_xfer,
 148         .functionality  = mb862xx_func,
 149 };
 150
 151 static struct i2c_adapter mb862xx_i2c_adapter = {
 152         .name           = "MB862xx I2C adapter",
 153         .algo           = &mb862xx_algo,
 154         .owner          = THIS_MODULE,
 155 };
 156
 157 int mb862xx_i2c_init(struct mb862xxfb_par *par)
 158 {
 159         int ret;
 160
 161         mb862xx_i2c_adapter.algo_data = par;
 162         par->adap = &mb862xx_i2c_adapter;
 163
 164         ret = i2c_add_adapter(par->adap);
 165         if (ret < 0) {
 166                 dev_err(par->dev, "failed to add %s\n",
 167                         mb862xx_i2c_adapter.name);
 168         }
 169         return ret;
 170 }
 171
 172 void mb862xx_i2c_exit(struct mb862xxfb_par *par)
 173 {
 174         if (par->adap) {
 175                 i2c_del_adapter(par->adap);
 176                 par->adap = NULL;
 177         }
 178 }