lpss_i2c: Change handling of controller enable/disable

This change modifies the lpss_i2c driver to behave more like
the Linux kernel driver.  In particular the controller is only
enabled when processing a transaction, and is disabled after.
This means that errors in one transaction will not affect later
transactions.

Also when disabling the controller the code is supposed to wait
on the enable bit in the "enable status" register and not in
the enable control register.  In order to get access to this
register the reg map was expanded to include all registers.

This was tested with the cr50 TPM driver to ensure that if a
transaction does fail that it can be successfully retried instead
of the bus being unusable.

Change-Id: I43a546d54996ba0f08550a801927b8f7a6690cda
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/16589
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

1 files changed, 27 insertions, 13 deletions

diff --git a/src/soc/intel/common/lpss_i2c.c b/src/soc/intel/common/lpss_i2c.c
index 0c8fec44b5..76c3d14d70 100644
--- a/src/soc/intel/common/lpss_i2c.c
+++ b/src/soc/intel/common/lpss_i2c.c
@@ -58,6 +58,19 @@ struct lpss_i2c_regs {
 	uint32_t rx_level;
 	uint32_t sda_hold;
 	uint32_t tx_abort_source;
+	uint32_t slv_data_nak_only;
+	uint32_t dma_cr;
+	uint32_t dma_tdlr;
+	uint32_t dma_rdlr;
+	uint32_t sda_setup;
+	uint32_t ack_general_call;
+	uint32_t enable_status;
+	uint32_t fs_spklen;
+	uint32_t hs_spklen;
+	uint32_t clr_restart_det;
+	uint32_t comp_param1;
+	uint32_t comp_version;
+	uint32_t comp_type;
 } __attribute__((packed));
 
 /* Use a ~4ms timeout for various operations */
@@ -153,7 +166,7 @@ static int lpss_i2c_disable(struct lpss_i2c_regs *regs)
 
 		/* Wait for enable bit to clear */
 		stopwatch_init_usecs_expire(&sw, LPSS_I2C_TIMEOUT_US);
-		while (read32(&regs->enable) & ENABLE_CONTROLLER)
+		while (read32(&regs->enable_status) & ENABLE_CONTROLLER)
 			if (stopwatch_expired(&sw))
 				return -1;
 	}
@@ -232,6 +245,7 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 	struct stopwatch sw;
 	struct lpss_i2c_regs *regs;
 	size_t byte;
+	int ret = -1;
 
 	if (count <= 0 || !segments)
 		return -1;
@@ -242,14 +256,11 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 		return -1;
 	}
 
-	if (!(read32(&regs->enable) & ENABLE_CONTROLLER)) {
-		printk(BIOS_ERR, "I2C bus %u not initialized\n", bus);
-		return -1;
-	}
+	lpss_i2c_enable(regs);
 
 	if (lpss_i2c_wait_for_bus_idle(regs)) {
 		printk(BIOS_ERR, "I2C timeout waiting for bus %u idle\n", bus);
-		return -1;
+		goto out;
 	}
 
 	/* Process each segment */
@@ -269,7 +280,7 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 				printk(BIOS_ERR, "I2C %s failed: bus %u "
 				       "addr 0x%02x\n", segments->read ?
 				       "read" : "write", bus, segments->chip);
-				return -1;
+				goto out;
 			}
 		}
 		segments++;
@@ -280,7 +291,7 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 	while (!(read32(&regs->raw_intr_stat) & INTR_STAT_STOP_DET)) {
 		if (stopwatch_expired(&sw)) {
 			printk(BIOS_ERR, "I2C stop bit not received\n");
-			return -1;
+			goto out;
 		}
 	}
 
@@ -290,7 +301,7 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 	/* Wait for the bus to go idle */
 	if (lpss_i2c_wait_for_bus_idle(regs)) {
 		printk(BIOS_ERR, "I2C timeout waiting for bus %u idle\n", bus);
-		return -1;
+		goto out;
 	}
 
 	/* Flush the RX FIFO in case it is not empty */
@@ -298,12 +309,17 @@ int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
 	while (read32(&regs->status) & STATUS_RX_FIFO_NOT_EMPTY) {
 		if (stopwatch_expired(&sw)) {
 			printk(BIOS_ERR, "I2C timeout flushing RX FIFO\n");
-			return -1;
+			goto out;
 		}
 		read32(&regs->cmd_data);
 	}
 
-	return 0;
+	ret = 0;
+
+out:
+	read32(&regs->clear_intr);
+	lpss_i2c_disable(regs);
+	return ret;
 }
 
 /*
@@ -519,8 +535,6 @@ int lpss_i2c_init(unsigned bus, enum i2c_speed speed)
 	/* Enable stop detection interrupt */
 	write32(&regs->intr_mask, INTR_STAT_STOP_DET);
 
-	lpss_i2c_enable(regs);
-
 	printk(BIOS_INFO, "LPSS I2C bus %u at 0x%p (%u KHz)\n",
 	       bus, regs, (speed ? : I2C_SPEED_FAST) / KHz);