diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-xlr.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-xlr.c | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-xlr.c b/drivers/i2c/busses/i2c-xlr.c new file mode 100644 index 000000000000..96d3fabd8883 --- /dev/null +++ b/drivers/i2c/busses/i2c-xlr.c @@ -0,0 +1,278 @@ +/* + * Copyright 2011, Netlogic Microsystems Inc. + * Copyright 2004, Matt Porter <mporter@kernel.crashing.org> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/io.h> +#include <linux/platform_device.h> + +/* XLR I2C REGISTERS */ +#define XLR_I2C_CFG 0x00 +#define XLR_I2C_CLKDIV 0x01 +#define XLR_I2C_DEVADDR 0x02 +#define XLR_I2C_ADDR 0x03 +#define XLR_I2C_DATAOUT 0x04 +#define XLR_I2C_DATAIN 0x05 +#define XLR_I2C_STATUS 0x06 +#define XLR_I2C_STARTXFR 0x07 +#define XLR_I2C_BYTECNT 0x08 +#define XLR_I2C_HDSTATIM 0x09 + +/* XLR I2C REGISTERS FLAGS */ +#define XLR_I2C_BUS_BUSY 0x01 +#define XLR_I2C_SDOEMPTY 0x02 +#define XLR_I2C_RXRDY 0x04 +#define XLR_I2C_ACK_ERR 0x08 +#define XLR_I2C_ARB_STARTERR 0x30 + +/* Register Values */ +#define XLR_I2C_CFG_ADDR 0xF8 +#define XLR_I2C_CFG_NOADDR 0xFA +#define XLR_I2C_STARTXFR_ND 0x02 /* No Data */ +#define XLR_I2C_STARTXFR_RD 0x01 /* Read */ +#define XLR_I2C_STARTXFR_WR 0x00 /* Write */ + +#define XLR_I2C_TIMEOUT 10 /* timeout per byte in msec */ + +/* + * On XLR/XLS, we need to use __raw_ IO to read the I2C registers + * because they are in the big-endian MMIO area on the SoC. + * + * The readl/writel implementation on XLR/XLS byteswaps, because + * those are for its little-endian PCI space (see arch/mips/Kconfig). + */ +static inline void xlr_i2c_wreg(u32 __iomem *base, unsigned int reg, u32 val) +{ + __raw_writel(val, base + reg); +} + +static inline u32 xlr_i2c_rdreg(u32 __iomem *base, unsigned int reg) +{ + return __raw_readl(base + reg); +} + +struct xlr_i2c_private { + struct i2c_adapter adap; + u32 __iomem *iobase; +}; + +static int xlr_i2c_tx(struct xlr_i2c_private *priv, u16 len, + u8 *buf, u16 addr) +{ + struct i2c_adapter *adap = &priv->adap; + unsigned long timeout, stoptime, checktime; + u32 i2c_status; + int pos, timedout; + u8 offset, byte; + + offset = buf[0]; + xlr_i2c_wreg(priv->iobase, XLR_I2C_ADDR, offset); + xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr); + xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_ADDR); + xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1); + + timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT); + stoptime = jiffies + timeout; + timedout = 0; + pos = 1; +retry: + if (len == 1) { + xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, + XLR_I2C_STARTXFR_ND); + } else { + xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos]); + xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, + XLR_I2C_STARTXFR_WR); + } + + while (!timedout) { + checktime = jiffies; + i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS); + + if (i2c_status & XLR_I2C_SDOEMPTY) { + pos++; + /* need to do a empty dataout after the last byte */ + byte = (pos < len) ? buf[pos] : 0; + xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, byte); + + /* reset timeout on successful xmit */ + stoptime = jiffies + timeout; + } + timedout = time_after(checktime, stoptime); + + if (i2c_status & XLR_I2C_ARB_STARTERR) { + if (timedout) + break; + goto retry; + } + + if (i2c_status & XLR_I2C_ACK_ERR) + return -EIO; + + if ((i2c_status & XLR_I2C_BUS_BUSY) == 0 && pos >= len) + return 0; + } + dev_err(&adap->dev, "I2C transmit timeout\n"); + return -ETIMEDOUT; +} + +static int xlr_i2c_rx(struct xlr_i2c_private *priv, u16 len, u8 *buf, u16 addr) +{ + struct i2c_adapter *adap = &priv->adap; + u32 i2c_status; + unsigned long timeout, stoptime, checktime; + int nbytes, timedout; + u8 byte; + + xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_NOADDR); + xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len); + xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr); + + timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT); + stoptime = jiffies + timeout; + timedout = 0; + nbytes = 0; +retry: + xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, XLR_I2C_STARTXFR_RD); + + while (!timedout) { + checktime = jiffies; + i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS); + if (i2c_status & XLR_I2C_RXRDY) { + if (nbytes > len) + return -EIO; /* should not happen */ + + /* we need to do a dummy datain when nbytes == len */ + byte = xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN); + if (nbytes < len) + buf[nbytes] = byte; + nbytes++; + + /* reset timeout on successful read */ + stoptime = jiffies + timeout; + } + + timedout = time_after(checktime, stoptime); + if (i2c_status & XLR_I2C_ARB_STARTERR) { + if (timedout) + break; + goto retry; + } + + if (i2c_status & XLR_I2C_ACK_ERR) + return -EIO; + + if ((i2c_status & XLR_I2C_BUS_BUSY) == 0) + return 0; + } + + dev_err(&adap->dev, "I2C receive timeout\n"); + return -ETIMEDOUT; +} + +static int xlr_i2c_xfer(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + struct i2c_msg *msg; + int i; + int ret = 0; + struct xlr_i2c_private *priv = i2c_get_adapdata(adap); + + for (i = 0; ret == 0 && i < num; i++) { + msg = &msgs[i]; + if (msg->flags & I2C_M_RD) + ret = xlr_i2c_rx(priv, msg->len, &msg->buf[0], + msg->addr); + else + ret = xlr_i2c_tx(priv, msg->len, &msg->buf[0], + msg->addr); + } + + return (ret != 0) ? ret : num; +} + +static u32 xlr_func(struct i2c_adapter *adap) +{ + /* Emulate SMBUS over I2C */ + return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C; +} + +static struct i2c_algorithm xlr_i2c_algo = { + .master_xfer = xlr_i2c_xfer, + .functionality = xlr_func, +}; + +static int __devinit xlr_i2c_probe(struct platform_device *pdev) +{ + struct xlr_i2c_private *priv; + struct resource *res; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + priv->iobase = devm_request_and_ioremap(&pdev->dev, res); + if (!priv->iobase) { + dev_err(&pdev->dev, "devm_request_and_ioremap failed\n"); + return -EBUSY; + } + + priv->adap.dev.parent = &pdev->dev; + priv->adap.owner = THIS_MODULE; + priv->adap.algo_data = priv; + priv->adap.algo = &xlr_i2c_algo; + priv->adap.nr = pdev->id; + priv->adap.class = I2C_CLASS_HWMON; + snprintf(priv->adap.name, sizeof(priv->adap.name), "xlr-i2c"); + + i2c_set_adapdata(&priv->adap, priv); + ret = i2c_add_numbered_adapter(&priv->adap); + if (ret < 0) { + dev_err(&priv->adap.dev, "Failed to add i2c bus.\n"); + return ret; + } + + platform_set_drvdata(pdev, priv); + dev_info(&priv->adap.dev, "Added I2C Bus.\n"); + return 0; +} + +static int __devexit xlr_i2c_remove(struct platform_device *pdev) +{ + struct xlr_i2c_private *priv; + + priv = platform_get_drvdata(pdev); + i2c_del_adapter(&priv->adap); + platform_set_drvdata(pdev, NULL); + return 0; +} + +static struct platform_driver xlr_i2c_driver = { + .probe = xlr_i2c_probe, + .remove = __devexit_p(xlr_i2c_remove), + .driver = { + .name = "xlr-i2cbus", + .owner = THIS_MODULE, + }, +}; + +module_platform_driver(xlr_i2c_driver); + +MODULE_AUTHOR("Ganesan Ramalingam <ganesanr@netlogicmicro.com>"); +MODULE_DESCRIPTION("XLR/XLS SoC I2C Controller driver"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:xlr-i2cbus"); |