[PATCH] powermac: Fix i2c on keywest based chips

The new i2c implementation for PowerMac has a regression that causes the
hardware to go out of state when probing non-existent devices. While
fixing that, I also found & fixed a couple of other corner cases. This
fixes booting with a pbbuttons version that scans the i2c bus for an LMU
controller among others. Tested on a dual G5 with thermal control (which
has heavy i2c activity) with no problem so far.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 35 insertions, 43 deletions

diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
index e14f9ac55cf4..df2343e1956b 100644
--- a/arch/powerpc/platforms/powermac/low_i2c.c
+++ b/arch/powerpc/platforms/powermac/low_i2c.c
@@ -231,6 +231,14 @@ static u8 kw_i2c_wait_interrupt(struct pmac_i2c_host_kw *host)
         return isr;
 }
 
+static void kw_i2c_do_stop(struct pmac_i2c_host_kw *host, int result)
+{
+        kw_write_reg(reg_control, KW_I2C_CTL_STOP);
+        host->state = state_stop;
+        host->result = result;
+}
+
+
 static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
 {
         u8 ack;
@@ -246,42 +254,36 @@ static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
         }
 
         if (isr == 0) {
+                printk(KERN_WARNING "low_i2c: Timeout in i2c transfer"
+                       " on keywest !\n");
                 if (host->state != state_stop) {
-                        DBG_LOW("KW: Timeout !\n");
-                        host->result = -EIO;
-                        goto stop;
-                }
-                if (host->state == state_stop) {
-                        ack = kw_read_reg(reg_status);
-                        if (ack & KW_I2C_STAT_BUSY)
-                                kw_write_reg(reg_status, 0);
-                        host->state = state_idle;
-                        kw_write_reg(reg_ier, 0x00);
-                        if (!host->polled)
-                                complete(&host->complete);
+                        kw_i2c_do_stop(host, -EIO);
+                        return;
                 }
+                ack = kw_read_reg(reg_status);
+                if (ack & KW_I2C_STAT_BUSY)
+                        kw_write_reg(reg_status, 0);
+                host->state = state_idle;
+                kw_write_reg(reg_ier, 0x00);
+                if (!host->polled)
+                        complete(&host->complete);
                 return;
         }
 
         if (isr & KW_I2C_IRQ_ADDR) {
                 ack = kw_read_reg(reg_status);
                 if (host->state != state_addr) {
-                        kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
                         WRONG_STATE("KW_I2C_IRQ_ADDR"); 
-                        host->result = -EIO;
-                        goto stop;
+                        kw_i2c_do_stop(host, -EIO);
                 }
                 if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
-                        host->result = -ENODEV;
-                        DBG_LOW("KW: NAK on address\n");
+                        host->result = -ENXIO;
                         host->state = state_stop;
-                        return;
+                        DBG_LOW("KW: NAK on address\n");
                 } else {
-                        if (host->len == 0) {
-                                kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
-                                goto stop;
-                        }
-                        if (host->rw) {
+                        if (host->len == 0)
+                                kw_i2c_do_stop(host, 0);
+                        else if (host->rw) {
                                 host->state = state_read;
                                 if (host->len > 1)
                                         kw_write_reg(reg_control,
@@ -308,25 +310,19 @@ static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
                         ack = kw_read_reg(reg_status);
                         if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
                                 DBG_LOW("KW: nack on data write\n");
-                                host->result = -EIO;
-                                goto stop;
+                                host->result = -EFBIG;
+                                host->state = state_stop;
                         } else if (host->len) {
                                 kw_write_reg(reg_data, *(host->data++));
                                 host->len--;
-                        } else {
-                                kw_write_reg(reg_control, KW_I2C_CTL_STOP);
-                                host->state = state_stop;
-                                host->result = 0;
-                        }
-                        kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
+                        } else
+                                kw_i2c_do_stop(host, 0);
                 } else {
-                        kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
                         WRONG_STATE("KW_I2C_IRQ_DATA"); 
-                        if (host->state != state_stop) {
-                                host->result = -EIO;
-                                goto stop;
-                        }
+                        if (host->state != state_stop)
+                                kw_i2c_do_stop(host, -EIO);
                 }
+                kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
         }
 
         if (isr & KW_I2C_IRQ_STOP) {
@@ -340,14 +336,10 @@ static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
                         complete(&host->complete);
         }
 
+        /* Below should only happen in manual mode which we don't use ... */
         if (isr & KW_I2C_IRQ_START)
                 kw_write_reg(reg_isr, KW_I2C_IRQ_START);
 
-        return;
- stop:
-        kw_write_reg(reg_control, KW_I2C_CTL_STOP);     
-        host->state = state_stop;
-        return;
 }
 
 /* Interrupt handler */
@@ -544,11 +536,11 @@ static struct pmac_i2c_host_kw *__init kw_i2c_host_init(struct device_node *np)
                 return NULL;
         }
 
-        /* Make sure IRA is disabled */
+        /* Make sure IRQ is disabled */
         kw_write_reg(reg_ier, 0);
 
         /* Request chip interrupt */
-        if (request_irq(host->irq, kw_i2c_irq, SA_SHIRQ, "keywest i2c", host))
+        if (request_irq(host->irq, kw_i2c_irq, 0, "keywest i2c", host))
                 host->irq = NO_IRQ;
 
         printk(KERN_INFO "KeyWest i2c @0x%08x irq %d %s\n",