diff options
Diffstat (limited to 'drivers/i2c/algos/i2c-algo-sgi.c')
| -rw-r--r-- | drivers/i2c/algos/i2c-algo-sgi.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/i2c/algos/i2c-algo-sgi.c b/drivers/i2c/algos/i2c-algo-sgi.c new file mode 100644 index 000000000000..422721b241e5 --- /dev/null +++ b/drivers/i2c/algos/i2c-algo-sgi.c @@ -0,0 +1,189 @@ +/* + * i2c-algo-sgi.c: i2c driver algorithms for SGI adapters. + * + * This file is subject to the terms and conditions of the GNU General Public + * License version 2 as published by the Free Software Foundation. + * + * Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/delay.h> + +#include <linux/i2c.h> +#include <linux/i2c-algo-sgi.h> + + +#define SGI_I2C_FORCE_IDLE (0 << 0) +#define SGI_I2C_NOT_IDLE (1 << 0) +#define SGI_I2C_WRITE (0 << 1) +#define SGI_I2C_READ (1 << 1) +#define SGI_I2C_RELEASE_BUS (0 << 2) +#define SGI_I2C_HOLD_BUS (1 << 2) +#define SGI_I2C_XFER_DONE (0 << 4) +#define SGI_I2C_XFER_BUSY (1 << 4) +#define SGI_I2C_ACK (0 << 5) +#define SGI_I2C_NACK (1 << 5) +#define SGI_I2C_BUS_OK (0 << 7) +#define SGI_I2C_BUS_ERR (1 << 7) + +#define get_control() adap->getctrl(adap->data) +#define set_control(val) adap->setctrl(adap->data, val) +#define read_data() adap->rdata(adap->data) +#define write_data(val) adap->wdata(adap->data, val) + + +static int wait_xfer_done(struct i2c_algo_sgi_data *adap) +{ + int i; + + for (i = 0; i < adap->xfer_timeout; i++) { + if ((get_control() & SGI_I2C_XFER_BUSY) == 0) + return 0; + udelay(1); + } + + return -ETIMEDOUT; +} + +static int wait_ack(struct i2c_algo_sgi_data *adap) +{ + int i; + + if (wait_xfer_done(adap)) + return -ETIMEDOUT; + for (i = 0; i < adap->ack_timeout; i++) { + if ((get_control() & SGI_I2C_NACK) == 0) + return 0; + udelay(1); + } + + return -ETIMEDOUT; +} + +static int force_idle(struct i2c_algo_sgi_data *adap) +{ + int i; + + set_control(SGI_I2C_FORCE_IDLE); + for (i = 0; i < adap->xfer_timeout; i++) { + if ((get_control() & SGI_I2C_NOT_IDLE) == 0) + goto out; + udelay(1); + } + return -ETIMEDOUT; +out: + if (get_control() & SGI_I2C_BUS_ERR) + return -EIO; + return 0; +} + +static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr, + int rd) +{ + if (rd) + set_control(SGI_I2C_NOT_IDLE); + /* Check if bus is idle, eventually force it to do so */ + if (get_control() & SGI_I2C_NOT_IDLE) + if (force_idle(adap)) + return -EIO; + /* Write out the i2c chip address and specify operation */ + set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE); + if (rd) + addr |= 1; + write_data(addr); + if (wait_ack(adap)) + return -EIO; + return 0; +} + +static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf, + unsigned int len) +{ + int i; + + set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE); + for (i = 0; i < len; i++) { + if (wait_xfer_done(adap)) + return -EIO; + buf[i] = read_data(); + } + set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE); + + return 0; + +} + +static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf, + unsigned int len) +{ + int i; + + /* We are already in write state */ + for (i = 0; i < len; i++) { + write_data(buf[i]); + if (wait_ack(adap)) + return -EIO; + } + return 0; +} + +static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, + int num) +{ + struct i2c_algo_sgi_data *adap = i2c_adap->algo_data; + struct i2c_msg *p; + int i, err = 0; + + for (i = 0; !err && i < num; i++) { + p = &msgs[i]; + err = do_address(adap, p->addr, p->flags & I2C_M_RD); + if (err || !p->len) + continue; + if (p->flags & I2C_M_RD) + err = i2c_read(adap, p->buf, p->len); + else + err = i2c_write(adap, p->buf, p->len); + } + + return err; +} + +static u32 sgi_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_SMBUS_EMUL; +} + +static struct i2c_algorithm sgi_algo = { + .name = "SGI algorithm", + .id = I2C_ALGO_SGI, + .master_xfer = sgi_xfer, + .functionality = sgi_func, +}; + +/* + * registering functions to load algorithms at runtime + */ +int i2c_sgi_add_bus(struct i2c_adapter *adap) +{ + adap->id |= sgi_algo.id; + adap->algo = &sgi_algo; + + return i2c_add_adapter(adap); +} + + +int i2c_sgi_del_bus(struct i2c_adapter *adap) +{ + return i2c_del_adapter(adap); +} + +EXPORT_SYMBOL(i2c_sgi_add_bus); +EXPORT_SYMBOL(i2c_sgi_del_bus); + +MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>"); +MODULE_DESCRIPTION("I2C-Bus SGI algorithm"); +MODULE_LICENSE("GPL"); |