[PATCH 15/16] fpga: machxo2: extend erase timeout for machxo2 FPGA

[Johannes Zink <j.zink@xxxxxxxxxxxxxx>]

Measurements showed that some FPGAs take significantly longer than the
default wait function supplied. The datasheet inidicates up to 30
seconds erase times for some MachXO2 FPGAs, depending on the number of
LUTs (and the corresponding configuration flash size).

Signed-off-by: Johannes Zink <j.zink@xxxxxxxxxxxxxx>
---
 drivers/fpga/machxo2-common.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/fpga/machxo2-common.c b/drivers/fpga/machxo2-common.c
index ccf9a50fc590..e8967cdee2c6 100644
--- a/drivers/fpga/machxo2-common.c
+++ b/drivers/fpga/machxo2-common.c
@@ -17,6 +17,8 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/property.h>
+#include <linux/iopoll.h>
+#include <linux/time.h>
 #include "machxo2-common.h"
 
 #define MACHXO2_LOW_DELAY_USEC          5
@@ -24,6 +26,8 @@
 #define MACHXO2_REFRESH_USEC            4800
 #define MACHXO2_MAX_BUSY_LOOP           128
 #define MACHXO2_MAX_REFRESH_LOOP        16
+#define MACHXO2_MAX_ERASE_USEC          (30 * USEC_PER_SEC)
+#define MACHXO2_ERASE_USEC_SLEEP        (20 * USEC_PER_MSEC)
 
 #define MACHXO2_PAGE_SIZE               16
 #define MACHXO2_BUF_SIZE                (MACHXO2_PAGE_SIZE + 4)
@@ -54,6 +58,18 @@
 #define ISC_ERASE_FEATURE_ROW	BIT(17)
 #define ISC_ERASE_UFM		BIT(19)
 
+static inline int machxo2_wait_until_not_busy_timeout(struct machxo2_common_priv *priv)
+{
+	int ret, pollret;
+	u32 status = MACHXO2_BUSY;
+
+	pollret = read_poll_timeout(priv->get_status, ret,
+				    (ret && ret != -EAGAIN) || !(status & MACHXO2_BUSY),
+				    MACHXO2_ERASE_USEC_SLEEP, MACHXO2_MAX_ERASE_USEC,
+				    true, priv, &status);
+
+	return ret ?: pollret;
+}
 
 static inline u8 get_err(u32 status)
 {
@@ -114,6 +130,12 @@ static int machxo2_cleanup(struct fpga_manager *mgr)
 	if (ret)
 		goto fail;
 
+	ret = machxo2_wait_until_not_busy_timeout(priv);
+	if (ret) {
+		dev_err(&mgr->dev, "Erase operation failed (%d)", ret);
+		goto fail;
+	}
+
 	ret = machxo2_wait_until_not_busy(priv);
 	if (ret)
 		goto fail;
@@ -192,9 +214,11 @@ static int machxo2_write_init(struct fpga_manager *mgr,
 	if (ret)
 		goto fail;
 
-	ret = machxo2_wait_until_not_busy(priv);
-	if (ret)
+	ret = machxo2_wait_until_not_busy_timeout(priv);
+	if (ret) {
+		dev_err(&mgr->dev, "Erase operation failed (%d)", ret);
 		goto fail;
+	}
 
 	priv->get_status(priv, &status);
 	if (status & MACHXO2_FAIL) {
-- 
2.30.2