mtd: st_spi_fsm: Supply a method to read from the FSM's FIFO

When invoked the driver will attempt to read any available data from
the FSM's data register. Any data collected from this FIFO would have
originated from the flash chip.

Acked-by Angus Clark <angus.clark@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
index 5e22c8688197..73e0f2731bcb 100644
--- a/drivers/mtd/devices/st_spi_fsm.c
+++ b/drivers/mtd/devices/st_spi_fsm.c
@@ -281,6 +281,32 @@ static void stfsm_wait_seq(struct stfsm *fsm)
 	dev_err(fsm->dev, "timeout on sequence completion\n");
 }
 
+static void stfsm_read_fifo(struct stfsm *fsm, uint32_t *buf,
+			    const uint32_t size)
+{
+	uint32_t remaining = size >> 2;
+	uint32_t avail;
+	uint32_t words;
+
+	dev_dbg(fsm->dev, "Reading %d bytes from FIFO\n", size);
+
+	BUG_ON((((uint32_t)buf) & 0x3) || (size & 0x3));
+
+	while (remaining) {
+		for (;;) {
+			avail = stfsm_fifo_available(fsm);
+			if (avail)
+				break;
+			udelay(1);
+		}
+		words = min(avail, remaining);
+		remaining -= words;
+
+		readsl(fsm->base + SPI_FAST_SEQ_DATA_REG, buf, words);
+		buf += words;
+	}
+}
+
 static int stfsm_set_mode(struct stfsm *fsm, uint32_t mode)
 {
 	int ret, timeout = 10;