/* * i2c-algo-sgi.c: i2c driver algorithm used by the VINO (SGI Indy) and * MACE (SGI O2) chips. * * 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 < 0) ? err : i; } static u32 sgi_func(struct i2c_adapter *adap) { return I2C_FUNC_SMBUS_EMUL; } static const struct i2c_algorithm sgi_algo = { .master_xfer = sgi_xfer, .functionality = sgi_func, }; /* * registering functions to load algorithms at runtime */ int i2c_sgi_add_bus(struct i2c_adapter *adap) { adap->algo = &sgi_algo; return i2c_add_adapter(adap); } EXPORT_SYMBOL(i2c_sgi_add_bus); MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>"); MODULE_DESCRIPTION("I2C-Bus SGI algorithm"); MODULE_LICENSE("GPL");