firmware: microchip: support writing bitstream info to flash

Updating the FPGA image might bring with it changes visible to Linux,
so it is helpful to also co-locate dt-overlays that describe the new
image contents. If these are packaged in a specific format [1] (detected
by first 4 bytes being MCHP, since FPGA images have no magic), load
the file to the reserved 1 MiB region immediately after the directory in
flash. The Beagle-V Fire's "gateware" already creates these files and
puts them in flash [2].

Link: https://github.com/polarfire-soc/polarfire-soc-documentation/blob/master/how-to/re-programming-the-fpga-from-linux.md#main-header-format
Link: https://openbeagle.org/beaglev-fire/gateware/-/blob/main/gateware_scripts/generate_gateware_overlays.py?ref_type=heads
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

diff --git a/drivers/firmware/microchip/mpfs-auto-update.c b/drivers/firmware/microchip/mpfs-auto-update.c
index 835a19a7a3a09eee12e2a8280450310c30278838..4711856f465aeb9b6bb380f4411ecfb918869ff1 100644 (file)
--- a/drivers/firmware/microchip/mpfs-auto-update.c
+++ b/drivers/firmware/microchip/mpfs-auto-update.c
@@ -71,8 +71,9 @@
 #define AUTO_UPDATE_UPGRADE_DIRECTORY  (AUTO_UPDATE_DIRECTORY_WIDTH * AUTO_UPDATE_UPGRADE_INDEX)
 #define AUTO_UPDATE_BLANK_DIRECTORY    (AUTO_UPDATE_DIRECTORY_WIDTH * AUTO_UPDATE_BLANK_INDEX)
 #define AUTO_UPDATE_DIRECTORY_SIZE     SZ_1K
-#define AUTO_UPDATE_RESERVED_SIZE      SZ_1M
-#define AUTO_UPDATE_BITSTREAM_BASE     (AUTO_UPDATE_DIRECTORY_SIZE + AUTO_UPDATE_RESERVED_SIZE)
+#define AUTO_UPDATE_INFO_BASE          AUTO_UPDATE_DIRECTORY_SIZE
+#define AUTO_UPDATE_INFO_SIZE          SZ_1M
+#define AUTO_UPDATE_BITSTREAM_BASE     (AUTO_UPDATE_DIRECTORY_SIZE + AUTO_UPDATE_INFO_SIZE)
 
 #define AUTO_UPDATE_TIMEOUT_MS         60000
 
@@ -86,6 +87,17 @@ struct mpfs_auto_update_priv {
        bool cancel_request;
 };
 
+static bool mpfs_auto_update_is_bitstream_info(const u8 *data, u32 size)
+{
+       if (size < 4)
+               return false;
+
+       if (data[0] == 0x4d && data[1] == 0x43 && data[2] == 0x48 && data[3] == 0x50)
+               return true;
+
+       return false;
+}
+
 static enum fw_upload_err mpfs_auto_update_prepare(struct fw_upload *fw_uploader, const u8 *data,
                                                   u32 size)
 {
@@ -289,22 +301,37 @@ static int mpfs_auto_update_write_bitstream(struct fw_upload *fw_uploader, const
        loff_t directory_address = AUTO_UPDATE_UPGRADE_DIRECTORY;
        size_t erase_size = AUTO_UPDATE_DIRECTORY_SIZE;
        size_t bytes_written = 0;
+       bool is_info = mpfs_auto_update_is_bitstream_info(data, size);
        u32 image_address;
        int ret;
 
        erase_size = round_up(erase_size, (u64)priv->flash->erasesize);
 
-       image_address = AUTO_UPDATE_BITSTREAM_BASE +
-               AUTO_UPDATE_UPGRADE_INDEX * priv->size_per_bitstream;
+       if (is_info)
+               image_address = AUTO_UPDATE_INFO_BASE;
+       else
+               image_address = AUTO_UPDATE_BITSTREAM_BASE +
+                               AUTO_UPDATE_UPGRADE_INDEX * priv->size_per_bitstream;
 
        buffer = devm_kzalloc(priv->dev, erase_size, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;
 
-       ret = mpfs_auto_update_set_image_address(priv, buffer, image_address, directory_address);
-       if (ret) {
-               dev_err(priv->dev, "failed to set image address in the SPI directory: %d\n", ret);
-               goto out;
+       /*
+        * For bitstream info, the descriptor is written to a fixed offset,
+        * so there is no need to set the image address.
+        */
+       if (!is_info) {
+               ret = mpfs_auto_update_set_image_address(priv, buffer, image_address, directory_address);
+               if (ret) {
+                       dev_err(priv->dev, "failed to set image address in the SPI directory: %d\n", ret);
+                       return ret;
+               }
+       } else {
+               if (size > AUTO_UPDATE_INFO_SIZE) {
+                       dev_err(priv->dev, "bitstream info exceeds permitted size\n");
+                       return -ENOSPC;
+               }
        }
 
        /*
@@ -336,6 +363,7 @@ static int mpfs_auto_update_write_bitstream(struct fw_upload *fw_uploader, const
        }
 
        *written = bytes_written;
+       dev_info(priv->dev, "Wrote 0x%zx bytes to the flash\n", bytes_written);
 
 out:
        devm_kfree(priv->dev, buffer);
@@ -362,6 +390,9 @@ static enum fw_upload_err mpfs_auto_update_write(struct fw_upload *fw_uploader,
                goto out;
        }
 
+       if (mpfs_auto_update_is_bitstream_info(data, size))
+               goto out;
+
        ret = mpfs_auto_update_verify_image(fw_uploader);
        if (ret)
                err = FW_UPLOAD_ERR_FW_INVALID;