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Commit 60162e49 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Paul Mackerras
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[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: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 28897731

arch/powerpc/platforms/powermac/low_i2c.c

+35 −43
Original line number Diff line number Diff line
@@ -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;
@@ -246,12 +254,12 @@ 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;

			kw_i2c_do_stop(host, -EIO);

			return;

		}

		if (host->state == state_stop) {

		ack = kw_read_reg(reg_status);

		if (ack & KW_I2C_STAT_BUSY)

			kw_write_reg(reg_status, 0);
@@ -259,29 +267,23 @@ static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr) 
		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_i2c_do_stop(host, 0);

		} 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_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",