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 #include <linux/export.h>
  17
  18 #include "mb862xxfb.h"
  19 #include "mb862xx_reg.h"
  20
  21 static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
  22 {
  23         struct mb862xxfb_par *par = adap->algo_data;
  24         u32 reg;
  25
  26         do {
  27                 udelay(1);
  28                 reg = inreg(i2c, GC_I2C_BCR);
  29                 if (reg & (I2C_INT | I2C_BER))
  30                         break;
  31         } while (1);
  32
  33         return (reg & I2C_BER) ? 0 : 1;
  34 }
  35
  36 static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
  37 {
  38         struct mb862xxfb_par *par = adap->algo_data;
  39
  40         outreg(i2c, GC_I2C_DAR, addr);
  41         outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
  42         outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
  43         if (!mb862xx_i2c_wait_event(adap))
  44                 return -EIO;
  45         par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
  46         return par->i2c_rs;
  47 }
  48
  49 static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
  50 {
  51         struct mb862xxfb_par *par = adap->algo_data;
  52
  53         outreg(i2c, GC_I2C_DAR, byte);
  54         outreg(i2c, GC_I2C_BCR, I2C_START);
  55         if (!mb862xx_i2c_wait_event(adap))
  56                 return -EIO;
  57         return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
  58 }
  59
  60 static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
  61 {
  62         struct mb862xxfb_par *par = adap->algo_data;
  63
  64         outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
  65         if (!mb862xx_i2c_wait_event(adap))
  66                 return 0;
  67         *byte = inreg(i2c, GC_I2C_DAR);
  68         return 1;
  69 }
  70
  71 void mb862xx_i2c_stop(struct i2c_adapter *adap)
  72 {
  73         struct mb862xxfb_par *par = adap->algo_data;
  74
  75         outreg(i2c, GC_I2C_BCR, I2C_STOP);
  76         outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
  77         par->i2c_rs = 0;
  78 }
  79
  80 static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
  81 {
  82         int i, ret = 0;
  83         int last = m->len - 1;
  84
  85         for (i = 0; i < m->len; i++) {
  86                 if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
  87                         ret = -EIO;
  88                         break;
  89                 }
  90         }
  91         return ret;
  92 }
  93
  94 static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
  95 {
  96         int i, ret = 0;
  97
  98         for (i = 0; i < m->len; i++) {
  99                 if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
 100                         ret = -EIO;
 101                         break;
 102                 }
 103         }
 104         return ret;
 105 }
 106
 107 static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 108                         int num)
 109 {
 110         struct mb862xxfb_par *par = adap->algo_data;
 111         struct i2c_msg *m;
 112         int addr;
 113         int i = 0, err = 0;
 114
 115         dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);
 116
 117         for (i = 0; i < num; i++) {
 118                 m = &msgs[i];
 119                 if (!m->len) {
 120                         dev_dbg(par->dev, "%s: null msgs\n", __func__);
 121                         continue;
 122                 }
 123                 addr = m->addr;
 124                 if (m->flags & I2C_M_RD)
 125                         addr |= 1;
 126
 127                 err = mb862xx_i2c_do_address(adap, addr);
 128                 if (err < 0)
 129                         break;
 130                 if (m->flags & I2C_M_RD)
 131                         err = mb862xx_i2c_read(adap, m);
 132                 else
 133                         err = mb862xx_i2c_write(adap, m);
 134         }
 135
 136         if (i)
 137                 mb862xx_i2c_stop(adap);
 138
 139         return (err < 0) ? err : i;
 140 }
 141
 142 static u32 mb862xx_func(struct i2c_adapter *adap)
 143 {
 144         return I2C_FUNC_SMBUS_BYTE_DATA;
 145 }
 146
 147 static const struct i2c_algorithm mb862xx_algo = {
 148         .master_xfer    = mb862xx_xfer,
 149         .functionality  = mb862xx_func,
 150 };
 151
 152 static struct i2c_adapter mb862xx_i2c_adapter = {
 153         .name           = "MB862xx I2C adapter",
 154         .algo           = &mb862xx_algo,
 155         .owner          = THIS_MODULE,
 156 };
 157
 158 int mb862xx_i2c_init(struct mb862xxfb_par *par)
 159 {
 160         int ret;
 161
 162         mb862xx_i2c_adapter.algo_data = par;
 163         par->adap = &mb862xx_i2c_adapter;
 164
 165         ret = i2c_add_adapter(par->adap);
 166         if (ret < 0) {
 167                 dev_err(par->dev, "failed to add %s\n",
 168                         mb862xx_i2c_adapter.name);
 169         }
 170         return ret;
 171 }
 172
 173 void mb862xx_i2c_exit(struct mb862xxfb_par *par)
 174 {
 175         if (par->adap) {
 176                 i2c_del_adapter(par->adap);
 177                 par->adap = NULL;
 178         }
 179 }