[Qemu-devel] [PATCH] hw/block/pflash_cfi01: Report correct size info for parallel configs

[Peter Maydell <peter.maydell@linaro.org>]

If the flash device is configured with a device-width which is
not equal to the bank-width, indicating that it is actually several
narrow flash devices in parallel, the CFI table should report the
number of blocks and the size of a single device, not of the whole
combined setup. This stops Linux from complaining:
"NOR chip too large to fit in mapping. Attempting to cope..."

As usual, we retain the old broken but backwards compatible behaviour
when the device-width is not specified.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
At the moment vexpress is the only board which properly sets device-width
rather than using the back-compat misemulated behaviour...

 hw/block/pflash_cfi01.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index 0c95d53..f9507b4 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -748,9 +748,18 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
     pflash_t *pfl = CFI_PFLASH01(dev);
     uint64_t total_len;
     int ret;
+    uint64_t blocks_per_device, device_len;
+    int num_devices;
 
     total_len = pfl->sector_len * pfl->nb_blocs;
 
+    /* These are only used to expose the parameters of each device
+     * in the cfi_table[].
+     */
+    num_devices = pfl->device_width ? (pfl->bank_width / pfl->device_width) : 1;
+    blocks_per_device = pfl->nb_blocs / num_devices;
+    device_len = pfl->sector_len * blocks_per_device;
+
     /* XXX: to be fixed */
 #if 0
     if (total_len != (8 * 1024 * 1024) && total_len != (16 * 1024 * 1024) &&
@@ -838,7 +847,7 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
     /* Max timeout for chip erase */
     pfl->cfi_table[0x26] = 0x00;
     /* Device size */
-    pfl->cfi_table[0x27] = ctz32(total_len); // + 1;
+    pfl->cfi_table[0x27] = ctz32(device_len); /* + 1; */
     /* Flash device interface (8 & 16 bits) */
     pfl->cfi_table[0x28] = 0x02;
     pfl->cfi_table[0x29] = 0x00;
@@ -854,8 +863,8 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
     /* Number of erase block regions (uniform) */
     pfl->cfi_table[0x2C] = 0x01;
     /* Erase block region 1 */
-    pfl->cfi_table[0x2D] = pfl->nb_blocs - 1;
-    pfl->cfi_table[0x2E] = (pfl->nb_blocs - 1) >> 8;
+    pfl->cfi_table[0x2D] = blocks_per_device - 1;
+    pfl->cfi_table[0x2E] = (blocks_per_device - 1) >> 8;
     pfl->cfi_table[0x2F] = pfl->sector_len >> 8;
     pfl->cfi_table[0x30] = pfl->sector_len >> 16;
 
@@ -882,6 +891,11 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
 
 static Property pflash_cfi01_properties[] = {
     DEFINE_PROP_DRIVE("drive", struct pflash_t, bs),
+    /* num-blocks is the number of blocks actually visible to the guest,
+     * ie the total size of the device divided by the sector length.
+     * If we're emulating flash devices wired in parallel the actual
+     * number of blocks per indvidual device will differ.
+     */
     DEFINE_PROP_UINT32("num-blocks", struct pflash_t, nb_blocs, 0),
     DEFINE_PROP_UINT64("sector-length", struct pflash_t, sector_len, 0),
     /* width here is the overall width of this QEMU device in bytes.
-- 
1.9.2