dfu: allow backend to specify a maximum buffer size

CONFIG_SYS_DFU_DATA_BUF_SIZE may be large to allow for FAT/ext layouts
to transfer large files. However, this means that individual write
operations will take a long time. Allow backends to specify a maximum
buffer size, so that each write operation is limited to a smaller data
block. This prevents the DFU protocol from timing out when e.g. writing
to SPI flash. I would guess that NAND might benefit from setting this
value too, but I can't test that.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

drivers/dfu/dfu.c

@@ -82,7 +82,7 @@ unsigned long dfu_get_buf_size(void)
 	return dfu_buf_size;
 }
 
-unsigned char *dfu_get_buf(void)
+unsigned char *dfu_get_buf(struct dfu_entity *dfu)
 {
 	char *s;
 
@@ -92,6 +92,8 @@ unsigned char *dfu_get_buf(void)
 	s = getenv("dfu_bufsiz");
 	dfu_buf_size = s ? (unsigned long)simple_strtol(s, NULL, 16) :
 			CONFIG_SYS_DFU_DATA_BUF_SIZE;
+	if (dfu->max_buf_size && dfu_buf_size > dfu->max_buf_size)
+		dfu_buf_size = dfu->max_buf_size;
 
 	dfu_buf = memalign(CONFIG_SYS_CACHELINE_SIZE, dfu_buf_size);
 	if (dfu_buf == NULL)
@@ -194,10 +196,10 @@ int dfu_write(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 		dfu->offset = 0;
 		dfu->bad_skip = 0;
 		dfu->i_blk_seq_num = 0;
-		dfu->i_buf_start = dfu_get_buf();
+		dfu->i_buf_start = dfu_get_buf(dfu);
 		if (dfu->i_buf_start == NULL)
 			return -ENOMEM;
-		dfu->i_buf_end = dfu_get_buf() + dfu_buf_size;
+		dfu->i_buf_end = dfu_get_buf(dfu) + dfu_buf_size;
 		dfu->i_buf = dfu->i_buf_start;
 
 		dfu->inited = 1;
@@ -318,7 +320,7 @@ int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 	       __func__, dfu->name, buf, size, blk_seq_num, dfu->i_buf);
 
 	if (!dfu->inited) {
-		dfu->i_buf_start = dfu_get_buf();
+		dfu->i_buf_start = dfu_get_buf(dfu);
 		if (dfu->i_buf_start == NULL)
 			return -ENOMEM;
 
@@ -342,7 +344,7 @@ int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 		dfu->i_blk_seq_num = 0;
 		dfu->crc = 0;
 		dfu->offset = 0;
-		dfu->i_buf_end = dfu_get_buf() + dfu_buf_size;
+		dfu->i_buf_end = dfu_get_buf(dfu) + dfu_buf_size;
 		dfu->i_buf = dfu->i_buf_start;
 		dfu->b_left = 0;
 
@@ -398,6 +400,7 @@ static int dfu_fill_entity(struct dfu_entity *dfu, char *s, int alt,
 	strcpy(dfu->name, st);
 
 	dfu->alt = alt;
+	dfu->max_buf_size = 0;
 
 	/* Specific for mmc device */
 	if (strcmp(interface, "mmc") == 0) {

drivers/usb/gadget/f_thor.c

@@ -142,7 +142,8 @@ static long long int download_head(unsigned long long total,
 				   int *cnt)
 {
 	long long int rcv_cnt = 0, left_to_rcv, ret_rcv;
-	void *transfer_buffer = dfu_get_buf();
+	struct dfu_entity *dfu_entity = dfu_get_entity(alt_setting_num);
+	void *transfer_buffer = dfu_get_buf(dfu_entity);
 	void *buf = transfer_buffer;
 	int usb_pkt_cnt = 0, ret;
 
@@ -205,7 +206,7 @@ static long long int download_head(unsigned long long total,
 static int download_tail(long long int left, int cnt)
 {
 	struct dfu_entity *dfu_entity = dfu_get_entity(alt_setting_num);
-	void *transfer_buffer = dfu_get_buf();
+	void *transfer_buffer = dfu_get_buf(dfu_entity);
 	int ret;
 
 	debug("%s: left: %llu cnt: %d\n", __func__, left, cnt);

include/dfu.h

@@ -91,6 +91,7 @@ struct dfu_entity {
 	void                    *dev_private;
 	enum dfu_device_type    dev_type;
 	enum dfu_layout         layout;
+	unsigned long           max_buf_size;
 
 	union {
 		struct mmc_internal_data mmc;
@@ -138,7 +139,7 @@ void dfu_trigger_reset(void);
 int dfu_get_alt(char *name);
 bool dfu_reset(void);
 int dfu_init_env_entities(char *interface, char *devstr);
-unsigned char *dfu_get_buf(void);
+unsigned char *dfu_get_buf(struct dfu_entity *dfu);
 unsigned char *dfu_free_buf(void);
 unsigned long dfu_get_buf_size(void);