[PATCH linux dev-4.7 v4 2/2] drivers/fsi: Cleanup and retry op on error

[Christopher Bostic]

On detect of FSI bus error clean up the bus and then retry
the original operation.

Signed-off-by: Christopher Bostic <cbostic at linux.vnet.ibm.com>

---
v4 - Move atomic_t from global to scope of fsi_master_handle_error

v3 - Move comon read/write code into a retry utility

   - Add comment on why trying again

   - Change nested error check from atomic bit type to atomic_t

   - loop on retry instead of duplicating the same code
---
 drivers/fsi/fsi-core.c        | 30 ++++++++++++++++++++++++++++++
 drivers/fsi/fsi-master-gpio.c | 28 ++++++++++++++++++++++++++--
 drivers/fsi/fsi-master.h      |  1 +
 3 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 8409c00..1114e53 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -42,6 +42,9 @@
 
 #define FSI_PEEK_BASE			0x410
 #define	FSI_SLAVE_BASE			0x800
+#define	FSI_HUB_CONTROL			0x3400
+
+#define	FSI_SLAVE_SMODE_DFLT		0xa0ff0100
 
 #define FSI_IPOLL_PERIOD		msecs_to_jiffies(fsi_ipoll_period_ms)
 
@@ -663,6 +666,33 @@ static int fsi_master_break(struct fsi_master *master, int link)
 	return 0;
 }
 
+void fsi_master_handle_error(struct fsi_master *master, uint32_t addr)
+{
+	uint32_t smode = FSI_SLAVE_SMODE_DFLT;
+	static atomic_t in_err_cleanup = ATOMIC_INIT(-1);
+
+	if (!atomic_inc_and_test(&in_err_cleanup))
+		return;
+
+	fsi_master_break(master, 0);
+	udelay(200);
+	master->write(master, 0, 0, FSI_SLAVE_BASE + FSI_SMODE, &smode,
+			sizeof(smode));
+	smode = FSI_MRESB_RST_GEN | FSI_MRESB_RST_ERR;
+	master->write(master, 0, 0, FSI_HUB_CONTROL + FSI_MRESB0, &smode,
+			sizeof(smode));
+
+	if (addr > FSI_HUB_LINK_OFFSET) {
+		smode = FSI_BREAK;
+		master->write(master, 0, 0, 0x100004, &smode, sizeof(smode));
+		smode = FSI_SLAVE_SMODE_DFLT;
+		master->write(master, 0, 0, 0x100800, &smode, sizeof(smode));
+	}
+
+	atomic_set(&in_err_cleanup, -1);
+}
+EXPORT_SYMBOL(fsi_master_handle_error);
+
 static int fsi_master_scan(struct fsi_master *master)
 {
 	int link, slave_id, rc;
diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index b6feec1..c5f4f9c 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -370,6 +370,28 @@ static int send_command(struct fsi_master_gpio *master,
 	return rc;
 }
 
+static int fsi_master_gpio_send(struct fsi_master_gpio *master,
+				struct fsi_gpio_msg *cmd, uint8_t expected,
+				uint32_t addr, size_t size, void *val)
+{
+	static const int master_retries = 2;
+	uint8_t retries;
+	int rc;
+
+	/*
+	 * In case the FSI bus is in a bad state a retry may help
+	 * the operation to complete successfully
+	 */
+	for (retries = 0; retries < master_retries; retries++) {
+		rc = send_command(master, cmd, expected, size, val);
+		if (!rc)
+			break;
+		fsi_master_handle_error(&master->master, addr);
+	}
+
+	return rc;
+}
+
 static int fsi_master_gpio_read(struct fsi_master *_master, int link,
 		uint8_t slave, uint32_t addr, void *val, size_t size)
 {
@@ -380,7 +402,8 @@ static int fsi_master_gpio_read(struct fsi_master *_master, int link,
 		return -ENODEV;
 
 	build_abs_ar_command(&cmd, FSI_GPIO_CMD_READ, slave, addr, size, NULL);
-	return send_command(master, &cmd, FSI_GPIO_RESP_ACKD, size, val);
+	return fsi_master_gpio_send(master, &cmd, FSI_GPIO_RESP_ACKD, addr,
+				size, val);
 }
 
 static int fsi_master_gpio_write(struct fsi_master *_master, int link,
@@ -393,7 +416,8 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
 		return -ENODEV;
 
 	build_abs_ar_command(&cmd, FSI_GPIO_CMD_WRITE, slave, addr, size, val);
-	return send_command(master, &cmd, FSI_GPIO_RESP_ACK, size, NULL);
+	return fsi_master_gpio_send(master, &cmd, FSI_GPIO_RESP_ACK, addr,
+				size, NULL);
 }
 
 /*
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index 4a3176b..54723a7 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -85,6 +85,7 @@ struct fsi_master {
 extern int fsi_master_register(struct fsi_master *master);
 extern void fsi_master_unregister(struct fsi_master *master);
 extern int fsi_master_start_ipoll(struct fsi_master *master);
+extern void fsi_master_handle_error(struct fsi_master *master, uint32_t addr);
 
 /**
  * crc4 helper: Given a starting crc4 state @c, calculate the crc4 vaue of @x,
-- 
1.8.2.2