OMAP4: HSI: SW WA for HSR in dead state after SW reset with pending errors

SW WA for HSI-C1BUG00088 "OMAP4430 HSI : No recovery from SW reset
under specific circumstances"

Description of issue:
It seems that in certain cases after some errors are detected by
HSR (frame timeout and/or tailing bit error and/or overrun), writing
the SW reset bit (SYSCONFIG.SOFTERESET to 1) may put the HSI in a
"dead" state in which it does not answer anymore to L4 OCP commands.
It seems that in certain cases after some errors are detected by HSR
(frame timeout and/or tailing bit error and/or overrun), writing the
SW reset bit (SYSCONFIG.SOFTERESET to 1) may put the HSI in a "dead"
state in which it does not answer anymore to L4 OCP commands.

Workaround is:
* Set HSR_MODE_P1.MODE_VAL = sleep and HSR_MODE_P2.MODE_VAL = sleep
* Acknowledge all errors (do not care if there is any) by writing
  HSR_ERRORACK_P1 and HSR_ERRORACK_P2
* Set SW reset

HW fix will be available for OMAP5430

Other changes:
* Removed write to Read only register HSI_HSR_BREAK_REG

Change-Id: I023d0fc8656808a8c294d7cfaec1bf3cb46da93f
Signed-off-by: Djamil Elaidi <d-elaidi@ti.com>

3 files changed, 24 insertions, 3 deletions

diff --git a/drivers/staging/omap_hsi/hsi_driver.c b/drivers/staging/omap_hsi/hsi_driver.c
index 8912dc0fc346..06368ea31886 100644
--- a/drivers/staging/omap_hsi/hsi_driver.c
+++ b/drivers/staging/omap_hsi/hsi_driver.c
@@ -272,12 +272,27 @@ void hsi_set_pm_force_hsi_on(struct hsi_dev *hsi_ctrl)
 	/* HSI_TODO : use the HWMOD API : omap_hwmod_set_slave_idlemode() */
 }
 
+/**
+* hsi_softreset - Force a SW RESET of HSI (core + DMA)
+*
+* @hsi_ctrl - reference to the hsi controller to be reset.
+*
+*/
 int hsi_softreset(struct hsi_dev *hsi_ctrl)
 {
 	unsigned int ind = 0;
+	unsigned int port;
 	void __iomem *base = hsi_ctrl->base;
 	u32 status;
 
+	/* SW WA for HSI-C1BUG00088 OMAP4430 HSI : No recovery from SW reset */
+	/* under specific circumstances  */
+	for (port = 1; port <= hsi_ctrl->max_p; port++) {
+		hsi_outl_and(HSI_HSR_MODE_MODE_VAL_SLEEP, base,
+			     HSI_HSR_MODE_REG(port));
+		hsi_outl(HSI_HSR_ERROR_ALL, base, HSI_HSR_ERRORACK_REG(port));
+	}
+
 	/* Reseting HSI Block */
 	hsi_outl_or(HSI_SOFTRESET, base, HSI_SYS_SYSCONFIG_REG);
 	do {
@@ -405,6 +420,13 @@ static int hsi_port_channels_reset(struct hsi_port *port)
 	return 0;
 }
 
+/**
+* hsi_softreset_driver - Must be called following HSI SW RESET, to re-align
+*			 variable states with new HW state.
+*
+* @hsi_ctrl - reference to the hsi controller to be re-aligned.
+*
+*/
 void hsi_softreset_driver(struct hsi_dev *hsi_ctrl)
 {
 	struct platform_device *pd = to_platform_device(hsi_ctrl->dev);
@@ -1000,7 +1022,7 @@ int hsi_runtime_suspend(struct device *dev)
 			     HSI_HSR_MODE_REG(port));
 	}
 
-	/* HSI is going to INA/RET/OFF, it needs IO wakeup mechanism enabled */
+	/* HSI is going to IDLE, it needs IO wakeup mechanism enabled */
 	if (device_may_wakeup(dev))
 		pdata->wakeup_enable(0);
 	else
diff --git a/drivers/staging/omap_hsi/hsi_driver_if.c b/drivers/staging/omap_hsi/hsi_driver_if.c
index 6a106e71922c..929bb938b914 100644
--- a/drivers/staging/omap_hsi/hsi_driver_if.c
+++ b/drivers/staging/omap_hsi/hsi_driver_if.c
@@ -676,7 +676,7 @@ EXPORT_SYMBOL(hsi_unpoll);
  * @command - HSI I/O control command
  * @arg - parameter associated to the control command. NULL, if no parameter.
  *
- * Return 0 on sucess, a negative value on failure.
+ * Return 0 on success, a negative value on failure.
  *
  */
 int hsi_ioctl(struct hsi_device *dev, unsigned int command, void *arg)
diff --git a/drivers/staging/omap_hsi/hsi_driver_int.c b/drivers/staging/omap_hsi/hsi_driver_int.c
index 1a6117c4ed06..94d859ab3f2c 100644
--- a/drivers/staging/omap_hsi/hsi_driver_int.c
+++ b/drivers/staging/omap_hsi/hsi_driver_int.c
@@ -562,7 +562,6 @@ static u32 hsi_driver_int_proc(struct hsi_port *pport,
 
 	if (status_reg & HSI_BREAKDETECTED) {
 		dev_info(hsi_ctrl->dev, "Hardware BREAK on port %d\n", port);
-		hsi_outl(0, base, HSI_HSR_BREAK_REG(port));
 		spin_unlock(&hsi_ctrl->lock);
 		hsi_port_event_handler(pport, HSI_EVENT_BREAK_DETECTED, NULL);
 		spin_lock(&hsi_ctrl->lock);