diff options
Diffstat (limited to 'drivers/i2c/algos/i2c-algo-pca.c')
| -rw-r--r-- | drivers/i2c/algos/i2c-algo-pca.c | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/drivers/i2c/algos/i2c-algo-pca.c b/drivers/i2c/algos/i2c-algo-pca.c new file mode 100644 index 0000000..c3d912c --- /dev/null +++ b/drivers/i2c/algos/i2c-algo-pca.c @@ -0,0 +1,399 @@ +/* + * i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters + * Copyright (C) 2004 Arcom Control Systems + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/delay.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/i2c-algo-pca.h> +#include "i2c-algo-pca.h" + +#define DRIVER "i2c-algo-pca" + +#define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0) +#define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0) +#define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0) + +static int i2c_debug=0; + +#define pca_outw(adap, reg, val) adap->write_byte(adap, reg, val) +#define pca_inw(adap, reg) adap->read_byte(adap, reg) + +#define pca_status(adap) pca_inw(adap, I2C_PCA_STA) +#define pca_clock(adap) adap->get_clock(adap) +#define pca_own(adap) adap->get_own(adap) +#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val) +#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON) +#define pca_wait(adap) adap->wait_for_interrupt(adap) + +/* + * Generate a start condition on the i2c bus. + * + * returns after the start condition has occured + */ +static void pca_start(struct i2c_algo_pca_data *adap) +{ + int sta = pca_get_con(adap); + DEB2("=== START\n"); + sta |= I2C_PCA_CON_STA; + sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); + pca_set_con(adap, sta); + pca_wait(adap); +} + +/* + * Generate a repeated start condition on the i2c bus + * + * return after the repeated start condition has occured + */ +static void pca_repeated_start(struct i2c_algo_pca_data *adap) +{ + int sta = pca_get_con(adap); + DEB2("=== REPEATED START\n"); + sta |= I2C_PCA_CON_STA; + sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); + pca_set_con(adap, sta); + pca_wait(adap); +} + +/* + * Generate a stop condition on the i2c bus + * + * returns after the stop condition has been generated + * + * STOPs do not generate an interrupt or set the SI flag, since the + * part returns the the idle state (0xf8). Hence we don't need to + * pca_wait here. + */ +static void pca_stop(struct i2c_algo_pca_data *adap) +{ + int sta = pca_get_con(adap); + DEB2("=== STOP\n"); + sta |= I2C_PCA_CON_STO; + sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI); + pca_set_con(adap, sta); +} + +/* + * Send the slave address and R/W bit + * + * returns after the address has been sent + */ +static void pca_address(struct i2c_algo_pca_data *adap, + struct i2c_msg *msg) +{ + int sta = pca_get_con(adap); + int addr; + + addr = ( (0x7f & msg->addr) << 1 ); + if (msg->flags & I2C_M_RD ) + addr |= 1; + DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n", + msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr); + + pca_outw(adap, I2C_PCA_DAT, addr); + + sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); + pca_set_con(adap, sta); + + pca_wait(adap); +} + +/* + * Transmit a byte. + * + * Returns after the byte has been transmitted + */ +static void pca_tx_byte(struct i2c_algo_pca_data *adap, + __u8 b) +{ + int sta = pca_get_con(adap); + DEB2("=== WRITE %#04x\n", b); + pca_outw(adap, I2C_PCA_DAT, b); + + sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); + pca_set_con(adap, sta); + + pca_wait(adap); +} + +/* + * Receive a byte + * + * returns immediately. + */ +static void pca_rx_byte(struct i2c_algo_pca_data *adap, + __u8 *b, int ack) +{ + *b = pca_inw(adap, I2C_PCA_DAT); + DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK"); +} + +/* + * Setup ACK or NACK for next received byte and wait for it to arrive. + * + * Returns after next byte has arrived. + */ +static void pca_rx_ack(struct i2c_algo_pca_data *adap, + int ack) +{ + int sta = pca_get_con(adap); + + sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA); + + if ( ack ) + sta |= I2C_PCA_CON_AA; + + pca_set_con(adap, sta); + pca_wait(adap); +} + +/* + * Reset the i2c bus / SIO + */ +static void pca_reset(struct i2c_algo_pca_data *adap) +{ + /* apparently only an external reset will do it. not a lot can be done */ + printk(KERN_ERR DRIVER ": Haven't figured out how to do a reset yet\n"); +} + +static int pca_xfer(struct i2c_adapter *i2c_adap, + struct i2c_msg *msgs, + int num) +{ + struct i2c_algo_pca_data *adap = i2c_adap->algo_data; + struct i2c_msg *msg = NULL; + int curmsg; + int numbytes = 0; + int state; + int ret; + + state = pca_status(adap); + if ( state != 0xF8 ) { + dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state ); + /* FIXME: what to do. Force stop ? */ + return -EREMOTEIO; + } + + DEB1("{{{ XFER %d messages\n", num); + + if (i2c_debug>=2) { + for (curmsg = 0; curmsg < num; curmsg++) { + int addr, i; + msg = &msgs[curmsg]; + + addr = (0x7f & msg->addr) ; + + if (msg->flags & I2C_M_RD ) + printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n", + curmsg, msg->len, addr, (addr<<1) | 1); + else { + printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s", + curmsg, msg->len, addr, addr<<1, + msg->len == 0 ? "" : ", "); + for(i=0; i < msg->len; i++) + printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", "); + printk("]\n"); + } + } + } + + curmsg = 0; + ret = -EREMOTEIO; + while (curmsg < num) { + state = pca_status(adap); + + DEB3("STATE is 0x%02x\n", state); + msg = &msgs[curmsg]; + + switch (state) { + case 0xf8: /* On reset or stop the bus is idle */ + pca_start(adap); + break; + + case 0x08: /* A START condition has been transmitted */ + case 0x10: /* A repeated start condition has been transmitted */ + pca_address(adap, msg); + break; + + case 0x18: /* SLA+W has been transmitted; ACK has been received */ + case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */ + if (numbytes < msg->len) { + pca_tx_byte(adap, msg->buf[numbytes]); + numbytes++; + break; + } + curmsg++; numbytes = 0; + if (curmsg == num) + pca_stop(adap); + else + pca_repeated_start(adap); + break; + + case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */ + DEB2("NOT ACK received after SLA+W\n"); + pca_stop(adap); + goto out; + + case 0x40: /* SLA+R has been transmitted; ACK has been received */ + pca_rx_ack(adap, msg->len > 1); + break; + + case 0x50: /* Data bytes has been received; ACK has been returned */ + if (numbytes < msg->len) { + pca_rx_byte(adap, &msg->buf[numbytes], 1); + numbytes++; + pca_rx_ack(adap, numbytes < msg->len - 1); + break; + } + curmsg++; numbytes = 0; + if (curmsg == num) + pca_stop(adap); + else + pca_repeated_start(adap); + break; + + case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */ + DEB2("NOT ACK received after SLA+R\n"); + pca_stop(adap); + goto out; + + case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */ + DEB2("NOT ACK received after data byte\n"); + goto out; + + case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */ + DEB2("Arbitration lost\n"); + goto out; + + case 0x58: /* Data byte has been received; NOT ACK has been returned */ + if ( numbytes == msg->len - 1 ) { + pca_rx_byte(adap, &msg->buf[numbytes], 0); + curmsg++; numbytes = 0; + if (curmsg == num) + pca_stop(adap); + else + pca_repeated_start(adap); + } else { + DEB2("NOT ACK sent after data byte received. " + "Not final byte. numbytes %d. len %d\n", + numbytes, msg->len); + pca_stop(adap); + goto out; + } + break; + case 0x70: /* Bus error - SDA stuck low */ + DEB2("BUS ERROR - SDA Stuck low\n"); + pca_reset(adap); + goto out; + case 0x90: /* Bus error - SCL stuck low */ + DEB2("BUS ERROR - SCL Stuck low\n"); + pca_reset(adap); + goto out; + case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */ + DEB2("BUS ERROR - Illegal START or STOP\n"); + pca_reset(adap); + goto out; + default: + printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state); + break; + } + + } + + ret = curmsg; + out: + DEB1(KERN_CRIT "}}} transfered %d/%d messages. " + "status is %#04x. control is %#04x\n", + curmsg, num, pca_status(adap), + pca_get_con(adap)); + return ret; +} + +static u32 pca_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static int pca_init(struct i2c_algo_pca_data *adap) +{ + static int freqs[] = {330,288,217,146,88,59,44,36}; + int own, clock; + + own = pca_own(adap); + clock = pca_clock(adap); + DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own); + DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]); + + pca_outw(adap, I2C_PCA_ADR, own << 1); + + pca_set_con(adap, I2C_PCA_CON_ENSIO | clock); + udelay(500); /* 500 µs for oscilator to stabilise */ + + return 0; +} + +static struct i2c_algorithm pca_algo = { + .name = "PCA9564 algorithm", + .id = I2C_ALGO_PCA, + .master_xfer = pca_xfer, + .functionality = pca_func, +}; + +/* + * registering functions to load algorithms at runtime + */ +int i2c_pca_add_bus(struct i2c_adapter *adap) +{ + struct i2c_algo_pca_data *pca_adap = adap->algo_data; + int rval; + + /* register new adapter to i2c module... */ + + adap->id |= pca_algo.id; + adap->algo = &pca_algo; + + adap->timeout = 100; /* default values, should */ + adap->retries = 3; /* be replaced by defines */ + + rval = pca_init(pca_adap); + + if (!rval) + i2c_add_adapter(adap); + + return rval; +} + +int i2c_pca_del_bus(struct i2c_adapter *adap) +{ + return i2c_del_adapter(adap); +} + +EXPORT_SYMBOL(i2c_pca_add_bus); +EXPORT_SYMBOL(i2c_pca_del_bus); + +MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>"); +MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm"); +MODULE_LICENSE("GPL"); + +module_param(i2c_debug, int, 0); |
