PatchSet 158 
Date: 2003/12/20 22:23:53
Log:
Make I2C speed on MPC5200 configurable by module parameter

Index: arch/ppc/kernel/ppc_ksyms.c
===================================================================
RCS file: /cvsroot/linuxppc_2_4_devel/arch/ppc/kernel/ppc_ksyms.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -u -r1.9 -r1.10
--- arch/ppc/kernel/ppc_ksyms.c	15 Nov 2003 01:11:32 -0000	1.9
+++ arch/ppc/kernel/ppc_ksyms.c	20 Dec 2003 22:23:53 -0000	1.10
@@ -355,7 +355,7 @@
 EXPORT_SYMBOL(debugger_fault_handler);
 #endif
 
-#if defined(CONFIG_8xx) || defined(CONFIG_4xx)
+#if defined(CONFIG_8xx) || defined(CONFIG_4xx) || defined(CONFIG_6xx)
 EXPORT_SYMBOL(__res);
 #endif
 #ifdef  CONFIG_8xx
Index: drivers/i2c/i2c-algo-mpc5xxx.c
===================================================================
RCS file: /cvsroot/linuxppc_2_4_devel/drivers/i2c/i2c-algo-mpc5xxx.c,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- drivers/i2c/i2c-algo-mpc5xxx.c	5 Dec 2003 11:59:56 -0000	1.2
+++ drivers/i2c/i2c-algo-mpc5xxx.c	20 Dec 2003 22:23:53 -0000	1.3
@@ -16,6 +16,9 @@
 #include <linux/string.h>
 #include <asm/io.h>
 #include <asm/mpc5xxx.h>
+#ifdef CONFIG_UBOOT
+#include <asm/ppcboot.h>
+#endif
 
 #include <linux/i2c.h>
 #include <linux/i2c-algo-ppc_5xxx.h>
@@ -24,6 +27,11 @@
 #define MPC5xxx_TIMEOUT	100
 #define MPC5xxx_RETRIES	3
 
+static int speed = 100;
+
+MODULE_PARM(speed, "i");
+
+
 static int mpc5xxx_in(volatile u32 *reg)
 {
 	return in_be32(reg) >> 24;
@@ -108,6 +116,53 @@
 	return 0;
 }
 
+static int mpc5xxx_get_fdr(void)
+{
+	int i2c_speed = speed * 1000;
+	ulong best_speed = 0;
+	ulong divider;
+	ulong scl;
+#ifdef CONFIG_UBOOT
+	extern unsigned char __res[];
+	bd_t *bd = (bd_t *)__res;
+	ulong ipb = bd->bi_ipbfreq;
+#else
+	ulong ipb = CONFIG_PPC_5xxx_IPBFREQ
+#endif
+	ulong bestmatch = 0xffffffffUL;
+	int best_i = 0, best_j = 0, i, j;
+	int SCL_Tap[] = { 9, 10, 12, 15, 5, 6, 7, 8};
+	struct {int scl2tap, tap2tap; } scltap[] = {
+		{4, 1},
+		{4, 2},
+		{6, 4},
+		{6, 8},
+		{14, 16},
+		{30, 32},
+		{62, 64},
+		{126, 128}
+	};
+	
+	for (i = 7; i >= 0; i--) {
+		for (j = 7; j >= 0; j--) {
+			scl = 2 * (scltap[j].scl2tap +
+				(SCL_Tap[i] - 1) * scltap[j].tap2tap + 2);
+			if (ipb <= i2c_speed*scl) {
+				if ((i2c_speed*scl - ipb) < bestmatch) {
+					bestmatch = i2c_speed*scl - ipb;
+					best_i = i;
+					best_j = j;
+					best_speed = ipb/scl;
+				}
+			}
+		}
+	}
+
+	divider = (best_i & 3) | ((best_i & 4) << 3) | (best_j << 2);
+
+	return divider;
+}
+
 static void mpc5xxx_init(struct i2c_algo_mpc5xxx_data *algo_data)
 {
 	struct mpc5xxx_i2c	*regs = algo_data->regs;
@@ -121,9 +176,7 @@
 	 */
 	mpc5xxx_out(&regs->madr, algo_data->addr, 0);
 	
-	/* Make clock run maximum slow.
-	 */
-	mpc5xxx_out(&regs->mfdr, MPC5xxx_I2C_100HZ, 0);
+	mpc5xxx_out(&regs->mfdr, mpc5xxx_get_fdr(), 0);
 
 	/* Enable module and disable interrupts.
 	 */
@@ -377,5 +430,5 @@
 
 EXPORT_SYMBOL(i2c_mpc5xxx_add_bus);
 EXPORT_SYMBOL(i2c_mpc5xxx_del_bus);
-MODULE_LICENSE("GPL")
+MODULE_LICENSE("GPL");