mec1322: fix flash_physical_read()

flashrom on target issues a salvo of flash read commands with small
buffer size (128 bytes). Since there is no yield this starves other
tasks/events including hooks and as result watchdog is never reloaded.
This change makes read function yield to other tasks. In addition,
spi_enable()/disable chaining leads to situations where a SPI can be
disabled in the middle of transcation. This is addressed by keeping
SPI permanently enabled in LFW entry function, as well as in RW/RO
early init functions.

BRANCH=None
BUG=chrome-os-partner:38103
TEST=manual on Cyan, run flashrom -p ec -w xx in cycles, swaping xx so that
flashrom does flash. Make sure there is no watchdog triggered

Change-Id: Id5c50239a1d5c64054d7c660dd03b2be4678221c
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/282111
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>

3 files changed, 6 insertions, 18 deletions

diff --git a/chip/mec1322/flash.c b/chip/mec1322/flash.c
index 679c64795a..a893ba7868 100644
--- a/chip/mec1322/flash.c
+++ b/chip/mec1322/flash.c
@@ -28,7 +28,6 @@ int flash_physical_read(int offset, int size, char *data)
 
 	offset += CONFIG_FLASH_BASE_SPI;
 
-	spi_enable(1);
 	for (i = 0; i < size; i += read_size) {
 		read_size = MIN((size - i), SPI_FLASH_MAX_READ_SIZE);
 		ret = spi_flash_read((uint8_t *)(data + i),
@@ -36,8 +35,9 @@ int flash_physical_read(int offset, int size, char *data)
 					read_size);
 		if (ret != EC_SUCCESS)
 			break;
+		/* yield so other tasks get a chance to wake up */
+		msleep(1);
 	}
-	spi_enable(0);
 
 	return ret;
 }
@@ -61,7 +61,6 @@ int flash_physical_write(int offset, int size, const char *data)
 	if ((offset | size | (uint32_t)(uintptr_t)data) & 3)
 		return EC_ERROR_INVAL;
 
-	spi_enable(1);
 	for (i = 0; i < size; i += write_size) {
 		write_size = MIN((size - i), SPI_FLASH_MAX_WRITE_SIZE);
 		ret = spi_flash_write(offset + i,
@@ -70,7 +69,6 @@ int flash_physical_write(int offset, int size, const char *data)
 		if (ret != EC_SUCCESS)
 			break;
 	}
-	spi_enable(0);
 	return ret;
 }
 
@@ -87,9 +85,7 @@ int flash_physical_erase(int offset, int size)
 	int ret;
 
 	offset += CONFIG_FLASH_BASE_SPI;
-	spi_enable(1);
 	ret = spi_flash_erase(offset, size);
-	spi_enable(0);
 	return ret;
 }
 
@@ -112,9 +108,7 @@ int flash_physical_get_protect(int bank)
 	uint32_t addr = bank * CONFIG_FLASH_BANK_SIZE;
 	int ret;
 
-	spi_enable(1);
 	ret = spi_flash_check_protect(addr, CONFIG_FLASH_BANK_SIZE);
-	spi_enable(0);
 	return ret;
 #else
 	return 0;
@@ -147,9 +141,7 @@ int flash_physical_protect_now(int all)
 		size = CONFIG_WP_SIZE;
 	}
 
-	spi_enable(1);
 	ret = spi_flash_set_protect(offset, size);
-	spi_enable(0);
 	return ret;
 #else
 	return 0;
@@ -175,14 +167,12 @@ uint32_t flash_physical_get_protect_flags(void)
  * scenarios
  */
 
-	spi_enable(1);
 	if (spi_flash_check_protect(CONFIG_RO_STORAGE_OFF, CONFIG_RO_SIZE)) {
 		flags |= EC_FLASH_PROTECT_RO_AT_BOOT | EC_FLASH_PROTECT_RO_NOW;
 		if (spi_flash_check_protect(CONFIG_RW_STORAGE_OFF,
 					    CONFIG_RW_SIZE))
 			flags |= EC_FLASH_PROTECT_ALL_NOW;
 	}
-	spi_enable(0);
 #endif
 	return flags;
 }
@@ -264,9 +254,7 @@ int flash_physical_protect_at_boot(enum flash_wp_range range)
 		break;
 	}
 
-	spi_enable(1);
 	ret = spi_flash_set_protect(offset, size);
-	spi_enable(0);
 	return ret;
 #else
 	return 0;
diff --git a/chip/mec1322/lfw/ec_lfw.c b/chip/mec1322/lfw/ec_lfw.c
index cd811b1c22..0f6d4d70c2 100644
--- a/chip/mec1322/lfw/ec_lfw.c
+++ b/chip/mec1322/lfw/ec_lfw.c
@@ -89,15 +89,11 @@ int spi_image_load(uint32_t offset)
 
 	memset((void *)buf, 0xFF, (CONFIG_FW_IMAGE_SIZE - 4));
 
-	spi_enable(1);
-
 	for (i = 0; i < CONFIG_FW_IMAGE_SIZE; i += SPI_CHUNK_SIZE)
 		spi_flash_readloc(&buf[i],
 					offset + i,
 					SPI_CHUNK_SIZE);
 
-	spi_enable(0);
-
 	return 0;
 
 }
@@ -235,6 +231,7 @@ void lfw_main()
 	dma_init();
 	uart_init();
 	system_init();
+	spi_enable(1);
 
 	uart_puts("littlefw");
 	uart_puts(version_data.version);
diff --git a/chip/mec1322/system.c b/chip/mec1322/system.c
index 04afff3c15..e29d8ce247 100644
--- a/chip/mec1322/system.c
+++ b/chip/mec1322/system.c
@@ -18,6 +18,7 @@
 #include "task.h"
 #include "timer.h"
 #include "util.h"
+#include "spi.h"
 
 /* Indices for hibernate data registers (RAM backed by VBAT) */
 enum hibdata_index {
@@ -118,6 +119,8 @@ void system_pre_init(void)
 		MEC1322_VBAT_RAM(MEC1322_IMAGETYPE_IDX) = 0;
 
 	check_reset_cause();
+
+	spi_enable(1);
 }
 
 void _system_reset(int flags, int wake_from_hibernate)