Subject: Re: [PATCH][RFC]Updated MPC I2C driver

From: Adrian Cox <[email-masked]>
Date: Thu, 01 Jul 2004 22:25:27 +0100

On Thu, 2004-07-01 at 15:59, Matthew McClintock wrote:
> 	The driver works well on both an mpc8540ads and a sandpoint here.
> However, I just learned yesterday that i2c 32-bit read/writes on the
> 85xx will not always be guaranteed to work.

It seems that the MPC107 is happy with 8 bit accesses to the registers,
so here's another version of the patch. This also changes the time
calculations to use time_after().

This still leaves the interrupt handling register of the MPC5200
unsolved. I suggest introducing another flag for the MPC5200, and adding
a small piece of extra setup code.

- Adrian Cox
Humboldt Solutions Ltd.

# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2004/07/01 22:10:01+01:00 [email-masked]
#   Switch to time_after for jiffies calculations
#
# drivers/i2c/busses/i2c-mpc.c
#   2004/07/01 22:09:50+01:00 [email-masked] +3 -3
#   Switch to time_after for jiffies calculations
#
# ChangeSet
#   2004/07/01 22:04:45+01:00 [email-masked]
#   Switch from readl/writel to readb/writeb for MPC85xx compatibility.
#
# drivers/i2c/busses/i2c-mpc.c
#   2004/07/01 22:04:32+01:00 [email-masked] +17 -17
#   Switch from readl/writel to readb/writeb for MPC85xx compatibility.
#
# ChangeSet
#   2004/07/01 17:53:05+01:00 [email-masked]
#   Add I2C driver for Motorola I2C
#
# drivers/i2c/busses/i2c-mpc.c
#   2004/07/01 17:52:55+01:00 [email-masked] +410 -0
#
# drivers/i2c/busses/i2c-mpc.c
#   2004/07/01 17:52:55+01:00 [email-masked] +0 -0
#   BitKeeper file /home/adrian/kernels/sa107-2.6/for-upstream/drivers/i2c/busses/i2c-mpc.c
#
# drivers/i2c/busses/Makefile
#   2004/07/01 17:52:55+01:00 [email-masked] +1 -0
#   Add I2C driver for Motorola I2C
#
# drivers/i2c/busses/Kconfig
#   2004/07/01 17:52:54+01:00 [email-masked] +11 -0
#   Add I2C driver for Motorola I2C
#
diff -Nru a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
--- a/drivers/i2c/busses/Kconfig	Thu Jul  1 22:20:58 2004
+++ b/drivers/i2c/busses/Kconfig	Thu Jul  1 22:20:58 2004
@@ -396,4 +396,15 @@
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-voodoo3.

+config I2C_MPC
+	tristate "MPC107/824x/85xx"
+	depends on I2C && FSL_OCP
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in I2C interface on the MPC107/Tsi107/MPC8240/MPC8245 and
+	  MPC85xx family processors.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mpc.
+
 endmenu
diff -Nru a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
--- a/drivers/i2c/busses/Makefile	Thu Jul  1 22:20:58 2004
+++ b/drivers/i2c/busses/Makefile	Thu Jul  1 22:20:58 2004
@@ -32,6 +32,7 @@
 obj-$(CONFIG_I2C_VOODOO3)	+= i2c-voodoo3.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 obj-$(CONFIG_SCx200_I2C)	+= scx200_i2c.o
+obj-$(CONFIG_I2C_MPC)	+= i2c-mpc.o

 ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
 EXTRA_CFLAGS += -DDEBUG
diff -Nru a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/drivers/i2c/busses/i2c-mpc.c	Thu Jul  1 22:20:58 2004
@@ -0,0 +1,410 @@
+/*
+ * (C) Copyright 2003-2004
+ * Humboldt Solutions Ltd, [email-masked].
+
+ * This is a combined i2c adapter and algorithm driver for the
+ * MPC107/Tsi107 PowerPC northbridge and processors that include
+ * the same I2C unit (8240, 8245, 85xx).
+ *
+ * Release 0.6
+ *
+ * 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., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <asm/io.h>
+#include <asm/ocp.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+
+#ifdef CONFIG_I2C_DEBUG_BUS
+#define DPRINTK(args...) printk(KERN_DEBUG __FILE__": " args)
+#else
+#define DPRINTK(args...)
+#endif
+
+
+#define MPC_I2C_ADDR  0x00
+#define MPC_I2C_FDR 	0x04
+#define MPC_I2C_CR	0x08
+#define MPC_I2C_SR	0x0c
+#define MPC_I2C_DR	0x10
+#define MPC_I2C_DFSRR 0x14
+#define MPC_I2C_REGION 0x20
+
+#define CCR_MEN  0x80
+#define CCR_MIEN 0x40
+#define CCR_MSTA 0x20
+#define CCR_MTX  0x10
+#define CCR_TXAK 0x08
+#define CCR_RSTA 0x04
+
+#define CSR_MCF  0x80
+#define CSR_MAAS 0x40
+#define CSR_MBB  0x20
+#define CSR_MAL  0x10
+#define CSR_SRW  0x04
+#define CSR_MIF  0x02
+#define CSR_RXAK 0x01
+
+struct mpc_i2c {
+	char *base;
+	struct ocp_def *ocpdef;
+	u32 interrupt;
+	wait_queue_head_t queue;
+	struct i2c_adapter adap;
+};
+
+static __inline__ void writeccr(struct mpc_i2c *i2c, u32 x)
+{
+	writeb(x, i2c->base + MPC_I2C_CR);
+}
+
+static irqreturn_t mpc_i2c_isr(int irq, void *dev_id, struct pt_regs * regs)
+{
+	struct mpc_i2c *i2c = dev_id;
+	if (readb(i2c->base + MPC_I2C_SR) & CSR_MIF) {
+		/* Read again to allow register to stabilise */
+		i2c->interrupt = readb(i2c->base + MPC_I2C_SR);
+		writeb(0, i2c->base + MPC_I2C_SR);
+		wake_up_interruptible(&i2c->queue);
+	}
+	return IRQ_HANDLED;
+}
+
+static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
+{
+	DECLARE_WAITQUEUE(wait, current);
+        unsigned long orig_jiffies = jiffies;
+        u32 x;
+	int result = 0;
+
+	if (i2c->ocpdef->irq == OCP_IRQ_NA) {
+		while(! (readb(i2c->base + MPC_I2C_SR) & CSR_MIF)) {
+			schedule();
+			if (time_after(jiffies, orig_jiffies + timeout)) {
+				DPRINTK("I2C: timeout\n");
+				result = -EIO;
+				break;
+			}
+		}
+		x = readb(i2c->base + MPC_I2C_SR);
+		writeb(0, i2c->base + MPC_I2C_SR);
+	} else {
+		add_wait_queue(&i2c->queue, &wait);
+		while ( ! (i2c->interrupt & CSR_MIF)) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			if (signal_pending(current)) {
+				DPRINTK("I2C: Interrupted\n");
+				result = -EINTR;
+				break;
+			}
+			if (time_after(jiffies, orig_jiffies + timeout)) {
+				DPRINTK("I2C: timeout\n");
+				result = -EIO;
+				break;
+			}
+			schedule_timeout(timeout);
+		}
+		current->state = TASK_RUNNING;
+		remove_wait_queue(&i2c->queue, &wait);
+		x = i2c->interrupt;
+		i2c->interrupt = 0;
+	}
+
+	if (result < -0)
+	    return result;
+
+	if (! (x & CSR_MCF))
+	{
+	    DPRINTK("I2C: unfinished\n");
+	    return -EIO;
+	}
+
+        if (x & CSR_MAL)
+	{
+	    	DPRINTK("I2C: MAL\n");
+                return -EIO;
+	}
+
+        if (writing && (x & CSR_RXAK)) {
+                DPRINTK("I2C: No RXAK\n");
+                /* generate stop */
+                writeccr(i2c, CCR_MEN);
+                return -EIO;
+        }
+        return 0;
+}
+
+static void mpc_i2c_start(struct mpc_i2c *i2c)
+{
+	struct ocp_fs_i2c_data *i2c_data = i2c->ocpdef->additions;
+        /* Set clock and filters */
+	if (i2c_data && (i2c_data->flags & FS_I2C_SEPARATE_DFSRR)) {
+		writeb(0x31, i2c->base + MPC_I2C_FDR);
+		writeb(0x10, i2c->base + MPC_I2C_DFSRR);
+	} else
+		writel(0x1031, i2c->base + MPC_I2C_FDR);
+        /* Clear arbitration */
+        writeb(0, i2c->base + MPC_I2C_SR);
+       	/* Start with MEN */
+	writeccr(i2c, CCR_MEN);
+}
+
+static void mpc_i2c_stop(struct mpc_i2c *i2c)
+{
+	writeccr(i2c, CCR_MEN);
+}
+
+static int mpc_write(struct mpc_i2c *i2c, int target,
+			const u8 *data, int length, int restart)
+{
+        int i;
+        unsigned timeout = HZ;
+    	u32 flags = restart ? CCR_RSTA : 0;
+
+	/* Start with MEN */
+	if (! restart)
+		writeccr(i2c, CCR_MEN);
+	/* Start as master */
+	writeccr(i2c, CCR_MIEN | CCR_MEN |
+		      CCR_MSTA | CCR_MTX | flags);
+	/* Write target byte */
+	writeb((target << 1), i2c->base + MPC_I2C_DR);
+
+	if (i2c_wait(i2c, timeout, 1) < 0)
+	    return -1;
+
+        for(i = 0; i < length; i++) {
+	        /* Write data byte */
+	        writeb(data[i], i2c->base + MPC_I2C_DR);
+
+	        if (i2c_wait(i2c, timeout, 1) < 0)
+	            return -1;
+        }
+
+        return 0;
+}
+
+static int mpc_read(struct mpc_i2c *i2c, int target,
+		       u8 *data, int length, int restart)
+{
+    	unsigned timeout = HZ;
+    	int i;
+    	u32 flags = restart ? CCR_RSTA : 0;
+
+	/* Start with MEN */
+	if (! restart)
+		writeccr(i2c, CCR_MEN);
+	/* Switch to read - restart */
+	writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA |
+		      CCR_MTX | flags);
+	/* Write target address byte - this time with the read flag set */
+	writeb((target << 1) | 1, i2c->base + MPC_I2C_DR);
+
+	if (i2c_wait(i2c, timeout, 0) < 0)
+	    return -1;
+
+	if (length == 1)
+	    writeccr(i2c, CCR_MIEN| CCR_MEN |
+			  CCR_MSTA | CCR_TXAK);
+	else
+	    writeccr(i2c, CCR_MIEN| CCR_MEN | CCR_MSTA);
+    	/* Dummy read */
+	readb(i2c->base + MPC_I2C_DR);
+
+	for(i = 0; i < length; i++) {
+		if (i2c_wait(i2c, timeout, 0) < 0)
+			return -1;
+
+		/* Generate txack on next to last byte */
+		if (i == length - 2)
+			writeccr(i2c, CCR_MIEN | CCR_MEN |
+				      CCR_MSTA | CCR_TXAK);
+		/* Generate stop on last byte */
+		if (i == length - 1)
+			writeccr(i2c, CCR_MIEN | CCR_MEN |
+				      CCR_TXAK);
+		data[i] = readb(i2c->base + MPC_I2C_DR);
+	}
+
+	return length;
+}
+
+static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+	                   int num)
+{
+	struct i2c_msg *pmsg;
+	int i;
+	int ret=0;
+        unsigned long orig_jiffies = jiffies;
+	struct mpc_i2c *i2c = i2c_get_adapdata(adap);
+
+        mpc_i2c_start(i2c);
+
+	/* Allow bus up to 1s to become not busy */
+	while(readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
+                if (signal_pending(current))
+		{
+			DPRINTK("I2C: Interrupted\n");
+                        return -EINTR;
+		}
+                if (time_after(jiffies, orig_jiffies + HZ))
+		{
+		    	printk("I2C: timeout\n");
+                        return -EIO;
+		}
+                schedule();
+        }
+
+	for (i = 0;ret >= 0 && i < num; i++) {
+		pmsg = &msgs[i];
+		DPRINTK("Doing %s %d bytes to 0x%02x - %d of %d messages\n",
+		     pmsg->flags & I2C_M_RD ? "read" : "write",
+                     pmsg->len, pmsg->addr, i + 1, num);
+		if (pmsg->flags & I2C_M_RD)
+                        ret = mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
+                else
+                        ret = mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
+        }
+        mpc_i2c_stop(i2c);
+        return (ret < 0) ? ret : num;
+}
+
+static u32 mpc_functionality(struct i2c_adapter *adap)
+{
+        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm mpc_algo = {
+	.name = "MPC algorithm",
+	.id = I2C_ALGO_MPC107,
+	.master_xfer = mpc_xfer,
+	.functionality = mpc_functionality,
+};
+
+static struct i2c_adapter mpc_ops = {
+	.owner = THIS_MODULE,
+	.name = "MPC adapter",
+	.id = I2C_ALGO_MPC107 | I2C_HW_MPC107,
+	.algo = &mpc_algo,
+	.class = I2C_CLASS_HWMON,
+	.timeout = 1,
+	.retries = 1
+};
+
+static int __devinit mpc_i2c_probe(struct ocp_device *ocp)
+{
+	int result = 0;
+	struct mpc_i2c *i2c;
+
+	if (!(i2c = kmalloc(sizeof(*i2c), GFP_KERNEL))){
+		return -ENOMEM;
+	}
+	i2c->ocpdef = ocp->def;
+	init_waitqueue_head(&i2c->queue);
+
+	if (! request_mem_region(ocp->def->paddr, MPC_I2C_REGION,
+		                 "i2c-mpc")) {
+		printk(KERN_ERR "i2c-mpc - resource unavailable\n");
+		return -ENODEV;
+	}
+
+	i2c->base = ioremap(ocp->def->paddr, MPC_I2C_REGION);
+
+	if (! i2c->base) {
+		printk(KERN_ERR "i2c-mpc - failed to map controller\n");
+		result = -ENOMEM;
+		goto fail_map;
+	}
+
+	if (ocp->def->irq != OCP_IRQ_NA)
+		if ((result = request_irq(ocp->def->irq, mpc_i2c_isr,
+					  0, "i2c-mpc", i2c)) < 0) {
+			printk(KERN_ERR "i2c-mpc - failed to attach interrupt\n");
+			goto fail_irq;
+		}
+
+	i2c->adap = mpc_ops;
+	i2c_set_adapdata(&i2c->adap, i2c);
+	if ((result = i2c_add_adapter(&i2c->adap)) < 0) {
+		printk(KERN_ERR "i2c-mpc - failed to add adapter\n");
+		goto fail_add;
+	}
+	ocp_set_drvdata(ocp, i2c);
+	return result;
+
+fail_add:
+	if (ocp->def->irq != OCP_IRQ_NA)
+		free_irq(ocp->def->irq, 0);
+fail_irq:
+	iounmap(i2c->base);
+fail_map:
+	release_mem_region(ocp->def->paddr, MPC_I2C_REGION);
+	kfree(i2c);
+	return result;
+}
+static void __devexit mpc_i2c_remove(struct ocp_device *ocp)
+{
+	struct mpc_i2c *i2c = ocp_get_drvdata(ocp);
+	ocp_set_drvdata(ocp, NULL);
+	i2c_del_adapter(&i2c->adap);
+
+	if (ocp->def->irq != OCP_IRQ_NA)
+		free_irq(i2c->ocpdef->irq, i2c);
+	iounmap(i2c->base);
+	release_mem_region(i2c->ocpdef->paddr, MPC_I2C_REGION);
+	kfree(i2c);
+}
+
+static struct ocp_device_id mpc_iic_ids[] __devinitdata =
+{
+	{ .vendor = OCP_VENDOR_FREESCALE, .function = OCP_FUNC_IIC },
+	{ .vendor = OCP_VENDOR_INVALID }
+};
+
+MODULE_DEVICE_TABLE(ocp, mpc_iic_ids);
+
+static struct ocp_driver mpc_iic_driver =
+{
+	.name 		= "iic",
+	.id_table	= mpc_iic_ids,
+	.probe		= mpc_i2c_probe,
+	.remove		= __devexit_p(mpc_i2c_remove)
+};
+
+static int __init iic_init(void)
+{
+	return ocp_register_driver(&mpc_iic_driver);
+}
+
+static void __exit iic_exit(void)
+{
+	ocp_unregister_driver(&mpc_iic_driver);
+}
+
+module_init(iic_init);
+module_exit(iic_exit);
+
+
+MODULE_AUTHOR("Adrian Cox <[email-masked]>");
+MODULE_DESCRIPTION("I2C-Bus adapter for MPC107 bridge and MPC824x/85xx processors");
+MODULE_LICENSE("GPL");