patch-2.4.25 linux-2.4.25/drivers/i2c/i2c-algo-sgi.c

• Lines: 190
• Date: 2004-02-18 05:36:31.000000000 -0800
• Orig file: linux-2.4.24/drivers/i2c/i2c-algo-sgi.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.24/drivers/i2c/i2c-algo-sgi.c linux-2.4.25/drivers/i2c/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");