drivers/i2c/busses/i2c-xlr.c

   1 /*
   2  * Copyright 2011, Netlogic Microsystems Inc.
   3  * Copyright 2004, Matt Porter <mporter@kernel.crashing.org>
   4  *
   5  * This file is licensed under the terms of the GNU General Public
   6  * License version 2.  This program is licensed "as is" without any
   7  * warranty of any kind, whether express or implied.
   8  */
   9
  10 #include <linux/err.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/ioport.h>
  15 #include <linux/delay.h>
  16 #include <linux/errno.h>
  17 #include <linux/i2c.h>
  18 #include <linux/io.h>
  19 #include <linux/platform_device.h>
  20
  21 /* XLR I2C REGISTERS */
  22 #define XLR_I2C_CFG             0x00
  23 #define XLR_I2C_CLKDIV          0x01
  24 #define XLR_I2C_DEVADDR         0x02
  25 #define XLR_I2C_ADDR            0x03
  26 #define XLR_I2C_DATAOUT         0x04
  27 #define XLR_I2C_DATAIN          0x05
  28 #define XLR_I2C_STATUS          0x06
  29 #define XLR_I2C_STARTXFR        0x07
  30 #define XLR_I2C_BYTECNT         0x08
  31 #define XLR_I2C_HDSTATIM        0x09
  32
  33 /* XLR I2C REGISTERS FLAGS */
  34 #define XLR_I2C_BUS_BUSY        0x01
  35 #define XLR_I2C_SDOEMPTY        0x02
  36 #define XLR_I2C_RXRDY           0x04
  37 #define XLR_I2C_ACK_ERR         0x08
  38 #define XLR_I2C_ARB_STARTERR    0x30
  39
  40 /* Register Values */
  41 #define XLR_I2C_CFG_ADDR        0xF8
  42 #define XLR_I2C_CFG_NOADDR      0xFA
  43 #define XLR_I2C_STARTXFR_ND     0x02    /* No Data */
  44 #define XLR_I2C_STARTXFR_RD     0x01    /* Read */
  45 #define XLR_I2C_STARTXFR_WR     0x00    /* Write */
  46
  47 #define XLR_I2C_TIMEOUT         10      /* timeout per byte in msec */
  48
  49 /*
  50  * On XLR/XLS, we need to use __raw_ IO to read the I2C registers
  51  * because they are in the big-endian MMIO area on the SoC.
  52  *
  53  * The readl/writel implementation on XLR/XLS byteswaps, because
  54  * those are for its little-endian PCI space (see arch/mips/Kconfig).
  55  */
  56 static inline void xlr_i2c_wreg(u32 __iomem *base, unsigned int reg, u32 val)
  57 {
  58         __raw_writel(val, base + reg);
  59 }
  60
  61 static inline u32 xlr_i2c_rdreg(u32 __iomem *base, unsigned int reg)
  62 {
  63         return __raw_readl(base + reg);
  64 }
  65
  66 struct xlr_i2c_private {
  67         struct i2c_adapter adap;
  68         u32 __iomem *iobase;
  69 };
  70
  71 static int xlr_i2c_tx(struct xlr_i2c_private *priv,  u16 len,
  72         u8 *buf, u16 addr)
  73 {
  74         struct i2c_adapter *adap = &priv->adap;
  75         unsigned long timeout, stoptime, checktime;
  76         u32 i2c_status;
  77         int pos, timedout;
  78         u8 offset, byte;
  79
  80         offset = buf[0];
  81         xlr_i2c_wreg(priv->iobase, XLR_I2C_ADDR, offset);
  82         xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);
  83         xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_ADDR);
  84         xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1);
  85
  86         timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
  87         stoptime = jiffies + timeout;
  88         timedout = 0;
  89         pos = 1;
  90 retry:
  91         if (len == 1) {
  92                 xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR,
  93                                 XLR_I2C_STARTXFR_ND);
  94         } else {
  95                 xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos]);
  96                 xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR,
  97                                 XLR_I2C_STARTXFR_WR);
  98         }
  99
 100         while (!timedout) {
 101                 checktime = jiffies;
 102                 i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
 103
 104                 if (i2c_status & XLR_I2C_SDOEMPTY) {
 105                         pos++;
 106                         /* need to do a empty dataout after the last byte */
 107                         byte = (pos < len) ? buf[pos] : 0;
 108                         xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, byte);
 109
 110                         /* reset timeout on successful xmit */
 111                         stoptime = jiffies + timeout;
 112                 }
 113                 timedout = time_after(checktime, stoptime);
 114
 115                 if (i2c_status & XLR_I2C_ARB_STARTERR) {
 116                         if (timedout)
 117                                 break;
 118                         goto retry;
 119                 }
 120
 121                 if (i2c_status & XLR_I2C_ACK_ERR)
 122                         return -EIO;
 123
 124                 if ((i2c_status & XLR_I2C_BUS_BUSY) == 0 && pos >= len)
 125                         return 0;
 126         }
 127         dev_err(&adap->dev, "I2C transmit timeout\n");
 128         return -ETIMEDOUT;
 129 }
 130
 131 static int xlr_i2c_rx(struct xlr_i2c_private *priv, u16 len, u8 *buf, u16 addr)
 132 {
 133         struct i2c_adapter *adap = &priv->adap;
 134         u32 i2c_status;
 135         unsigned long timeout, stoptime, checktime;
 136         int nbytes, timedout;
 137         u8 byte;
 138
 139         xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_NOADDR);
 140         xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len);
 141         xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);
 142
 143         timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
 144         stoptime = jiffies + timeout;
 145         timedout = 0;
 146         nbytes = 0;
 147 retry:
 148         xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, XLR_I2C_STARTXFR_RD);
 149
 150         while (!timedout) {
 151                 checktime = jiffies;
 152                 i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
 153                 if (i2c_status & XLR_I2C_RXRDY) {
 154                         if (nbytes > len)
 155                                 return -EIO;    /* should not happen */
 156
 157                         /* we need to do a dummy datain when nbytes == len */
 158                         byte = xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN);
 159                         if (nbytes < len)
 160                                 buf[nbytes] = byte;
 161                         nbytes++;
 162
 163                         /* reset timeout on successful read */
 164                         stoptime = jiffies + timeout;
 165                 }
 166
 167                 timedout = time_after(checktime, stoptime);
 168                 if (i2c_status & XLR_I2C_ARB_STARTERR) {
 169                         if (timedout)
 170                                 break;
 171                         goto retry;
 172                 }
 173
 174                 if (i2c_status & XLR_I2C_ACK_ERR)
 175                         return -EIO;
 176
 177                 if ((i2c_status & XLR_I2C_BUS_BUSY) == 0)
 178                         return 0;
 179         }
 180
 181         dev_err(&adap->dev, "I2C receive timeout\n");
 182         return -ETIMEDOUT;
 183 }
 184
 185 static int xlr_i2c_xfer(struct i2c_adapter *adap,
 186         struct i2c_msg *msgs, int num)
 187 {
 188         struct i2c_msg *msg;
 189         int i;
 190         int ret = 0;
 191         struct xlr_i2c_private *priv = i2c_get_adapdata(adap);
 192
 193         for (i = 0; ret == 0 && i < num; i++) {
 194                 msg = &msgs[i];
 195                 if (msg->flags & I2C_M_RD)
 196                         ret = xlr_i2c_rx(priv, msg->len, &msg->buf[0],
 197                                         msg->addr);
 198                 else
 199                         ret = xlr_i2c_tx(priv, msg->len, &msg->buf[0],
 200                                         msg->addr);
 201         }
 202
 203         return (ret != 0) ? ret : num;
 204 }
 205
 206 static u32 xlr_func(struct i2c_adapter *adap)
 207 {
 208         /* Emulate SMBUS over I2C */
 209         return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C;
 210 }
 211
 212 static struct i2c_algorithm xlr_i2c_algo = {
 213         .master_xfer    = xlr_i2c_xfer,
 214         .functionality  = xlr_func,
 215 };
 216
 217 static int xlr_i2c_probe(struct platform_device *pdev)
 218 {
 219         struct xlr_i2c_private  *priv;
 220         struct resource *res;
 221         int ret;
 222
 223         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 224         if (!priv)
 225                 return -ENOMEM;
 226
 227         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 228         priv->iobase = devm_ioremap_resource(&pdev->dev, res);
 229         if (IS_ERR(priv->iobase))
 230                 return PTR_ERR(priv->iobase);
 231
 232         priv->adap.dev.parent = &pdev->dev;
 233         priv->adap.owner        = THIS_MODULE;
 234         priv->adap.algo_data    = priv;
 235         priv->adap.algo         = &xlr_i2c_algo;
 236         priv->adap.nr           = pdev->id;
 237         priv->adap.class        = I2C_CLASS_HWMON;
 238         snprintf(priv->adap.name, sizeof(priv->adap.name), "xlr-i2c");
 239
 240         i2c_set_adapdata(&priv->adap, priv);
 241         ret = i2c_add_numbered_adapter(&priv->adap);
 242         if (ret < 0) {
 243                 dev_err(&priv->adap.dev, "Failed to add i2c bus.\n");
 244                 return ret;
 245         }
 246
 247         platform_set_drvdata(pdev, priv);
 248         dev_info(&priv->adap.dev, "Added I2C Bus.\n");
 249         return 0;
 250 }
 251
 252 static int xlr_i2c_remove(struct platform_device *pdev)
 253 {
 254         struct xlr_i2c_private *priv;
 255
 256         priv = platform_get_drvdata(pdev);
 257         i2c_del_adapter(&priv->adap);
 258         return 0;
 259 }
 260
 261 static struct platform_driver xlr_i2c_driver = {
 262         .probe  = xlr_i2c_probe,
 263         .remove = xlr_i2c_remove,
 264         .driver = {
 265                 .name   = "xlr-i2cbus",
 266         },
 267 };
 268
 269 module_platform_driver(xlr_i2c_driver);
 270
 271 MODULE_AUTHOR("Ganesan Ramalingam <ganesanr@netlogicmicro.com>");
 272 MODULE_DESCRIPTION("XLR/XLS SoC I2C Controller driver");
 273 MODULE_LICENSE("GPL v2");
 274 MODULE_ALIAS("platform:xlr-i2cbus");