[PATCH 3/9] memory: emif: handle overflow for timing for LP mode

[Lokesh Vutla]

From: Nishanth Menon <nm at ti.com>

In case the custom timings provide values which overflow
the maximum possible field value, warn and use maximum
permissible value.

Signed-off-by: Nishanth Menon <nm at ti.com>
---
 drivers/memory/emif.c |   36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/memory/emif.c b/drivers/memory/emif.c
index 69a480d..27a3ce1 100644
--- a/drivers/memory/emif.c
+++ b/drivers/memory/emif.c
@@ -714,6 +714,8 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)
 	u32 timeout_perf	= EMIF_LP_MODE_TIMEOUT_PERFORMANCE;
 	u32 timeout_pwr		= EMIF_LP_MODE_TIMEOUT_POWER;
 	u32 freq_threshold	= EMIF_LP_MODE_FREQ_THRESHOLD;
+	u32 mask;
+	u8 shift;
 
 	struct emif_custom_configs *cust_cfgs = emif->plat_data->custom_configs;
 
@@ -738,27 +740,45 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)
 
 	switch (lpmode) {
 	case EMIF_LP_MODE_CLOCK_STOP:
-		pwr_mgmt_ctrl = (timeout << CS_TIM_SHIFT) |
-					SR_TIM_MASK | PD_TIM_MASK;
+		shift = CS_TIM_SHIFT;
+		mask = CS_TIM_MASK;
 		break;
 	case EMIF_LP_MODE_SELF_REFRESH:
 		/* Workaround for errata i735 */
 		if (timeout < 6)
 			timeout = 6;
 
-		pwr_mgmt_ctrl = (timeout << SR_TIM_SHIFT) |
-					CS_TIM_MASK | PD_TIM_MASK;
+		shift = SR_TIM_SHIFT;
+		mask = SR_TIM_MASK;
 		break;
 	case EMIF_LP_MODE_PWR_DN:
-		pwr_mgmt_ctrl = (timeout << PD_TIM_SHIFT) |
-					CS_TIM_MASK | SR_TIM_MASK;
+		shift = PD_TIM_SHIFT;
+		mask = PD_TIM_MASK;
 		break;
 	case EMIF_LP_MODE_DISABLE:
 	default:
-		pwr_mgmt_ctrl = CS_TIM_MASK |
-					PD_TIM_MASK | SR_TIM_MASK;
+		mask = 0;
+		shift = 0;
+		break;
+	}
+	/* Round to maximum in case of overflow, BUT warn! */
+	if (lpmode != EMIF_LP_MODE_DISABLE && timeout > mask >> shift) {
+		pr_err("TIMEOUT Overflow - lpmode=%d perf=%d pwr=%d freq=%d\n",
+		       lpmode,
+		       timeout_perf,
+		       timeout_pwr,
+		       freq_threshold);
+		WARN(1, "timeout=0x%02x greater than 0x%02x. Using max\n",
+		     timeout, mask >> shift);
+		timeout = mask >> shift;
 	}
 
+	/* Setup required timing */
+	pwr_mgmt_ctrl = (timeout << shift) & mask;
+	/* setup a default mask for rest of the modes */
+	pwr_mgmt_ctrl |= (SR_TIM_MASK | CS_TIM_MASK | PD_TIM_MASK) &
+			  ~mask;
+
 	/* No CS_TIM in EMIF_4D5 */
 	if (ip_rev == EMIF_4D5)
 		pwr_mgmt_ctrl &= ~CS_TIM_MASK;
-- 
1.7.9.5