linux_spi: Dynamically detect max buffer size
Read max buffer size from sysfs if available.
Change-Id: Ic541e548ced8488f074d388f1c92174cad123064
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Signed-off-by: David Hendricks <dhendricks@fb.com>
Reviewed-on: https://review.coreboot.org/22441
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/linux_spi.c b/linux_spi.c
index e51fbc4..611559a 100644
--- a/linux_spi.c
+++ b/linux_spi.c
@@ -42,6 +42,8 @@
*/
static int fd = -1;
+#define BUF_SIZE_FROM_SYSFS "/sys/module/spidev/parameters/bufsiz"
+static size_t max_kernel_buf_size;
static int linux_spi_shutdown(void *data);
static int linux_spi_send_command(struct flashctx *flash, unsigned int writecnt,
@@ -127,8 +129,45 @@
return 1;
}
- register_spi_master(&spi_master_linux);
+ /* Read max buffer size from sysfs, or use page size as fallback. */
+ FILE *fp;
+ fp = fopen(BUF_SIZE_FROM_SYSFS, "r");
+ if (!fp) {
+ msg_pwarn("Cannot open %s: %s.\n", BUF_SIZE_FROM_SYSFS, strerror(errno));
+ goto out;
+ }
+ char buf[10];
+ memset(buf, 0, sizeof(buf));
+ if (!fread(buf, 1, sizeof(buf) - 1, fp)) {
+ if (feof(fp))
+ msg_pwarn("Cannot read %s: file is empty.\n", BUF_SIZE_FROM_SYSFS);
+ else
+ msg_pwarn("Cannot read %s: %s.\n", BUF_SIZE_FROM_SYSFS, strerror(errno));
+ goto out;
+ }
+
+ long int tmp;
+ errno = 0;
+ tmp = strtol(buf, NULL, 0);
+ if ((tmp < 0) || errno) {
+ msg_pwarn("Buffer size %ld from %s seems wrong.\n", tmp, BUF_SIZE_FROM_SYSFS);
+ } else {
+ msg_pdbg("%s: Using value from %s as max buffer size.\n", __func__, BUF_SIZE_FROM_SYSFS);
+ max_kernel_buf_size = (size_t)tmp;
+ }
+
+out:
+ if (fp)
+ fclose(fp);
+
+ if (!max_kernel_buf_size) {
+ msg_pdbg("%s: Using page size as max buffer size.\n", __func__);
+ max_kernel_buf_size = (size_t)getpagesize();
+ }
+
+ msg_pdbg("%s: max_kernel_buf_size: %zu\n", __func__, max_kernel_buf_size);
+ register_spi_master(&spi_master_linux);
return 0;
}
@@ -179,17 +218,16 @@
return 0;
}
-static int linux_spi_read(struct flashctx *flash, uint8_t *buf,
- unsigned int start, unsigned int len)
+static int linux_spi_read(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
{
- return spi_read_chunked(flash, buf, start, len,
- (unsigned int)getpagesize());
+ /* Read buffer is fully utilized for data. */
+ return spi_read_chunked(flash, buf, start, len, max_kernel_buf_size);
}
static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
{
- return spi_write_chunked(flash, buf, start, len,
- ((unsigned int)getpagesize()) - 4);
+ /* 5 bytes must be reserved for longest possible command + address. */
+ return spi_write_chunked(flash, buf, start, len, max_kernel_buf_size - 5);
}
#endif // CONFIG_LINUX_SPI == 1