spi: nuc900: Fix setting multiple bits settings in register

PATCH In review Axel Lin 2 participants 3 messages Mar 21, 2014 – Mar 27, 2014 1 message not in the archive SPI

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Axel Lin

author

2014-03-21 14:40 UTC #0 lore raw

PATCH v2 1/1 spi: nuc900: Fix setting multiple bits settings in register

The correct way to set multiple bits settings is always clear these bit fields before set new settings.

Current code does not cause problem because the reset value of these bit fields are 0, and these settings only set once during probe.

Signed-off-by Axel Lin <[email protected]>

---
 drivers/spi/spi-nuc900.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

drivers/spi/spi-nuc900.c +6 ~~-16~~

index 675c210..a062a89 100644
@@ -37,7 +37,9 @@
 /* usi register bit */
 #define ENINT		(0x01 << 17)
 #define ENFLG		(0x01 << 16)
+#define SLEEP		(0x0f << 12)
 #define TXNUM		(0x03 << 8)
+#define TXBITLEN	(0x1f << 3)
 #define TXNEG		(0x01 << 2)
 #define RXNEG		(0x01 << 1)
 #define LSB		(0x01 << 10)

@@ -115,8 +117,7 @@ static void nuc900_spi_chipsel(struct spi_device *spi, int value)
 	}
 }
 
-static void nuc900_spi_setup_txnum(struct nuc900_spi *hw,
-							unsigned int txnum)
+static void nuc900_spi_setup_txnum(struct nuc900_spi *hw, unsigned int txnum)
 {
 	unsigned int val;
 	unsigned long flags;

@@ -124,12 +125,7 @@ static void nuc900_spi_setup_txnum(struct nuc900_spi *hw,
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	if (!txnum)
-		val &= ~TXNUM;
-	else
-		val |= txnum << 0x08;
-
+	val = (val & ~TXNUM) | (txnum << 0x08);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);

@@ -145,9 +141,7 @@ static void nuc900_spi_setup_txbitlen(struct nuc900_spi *hw,
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	val |= (txbitlen << 0x03);
-
+	val = (val & ~TXBITLEN) | (txbitlen << 0x03);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);

@@ -284,11 +278,7 @@ static void nuc900_set_sleep(struct nuc900_spi *hw, unsigned int sleep)
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	if (sleep)
-		val |= (sleep << 12);
-	else
-		val &= ~(0x0f << 12);
+	val = (val & ~SLEEP) | (sleep << 12);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);

Signature · 8 lines

1.8.3.2



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Mark Brown

2014-03-26 16:48 UTC #1 lore raw

Quoted 5 lines · Axel Lin

The correct way to set multiple bits settings is always clear these bit fields before set new settings.
Current code does not cause problem because the reset value of these bit fields are 0, and these settings only set once during probe.

This doesn't seem to apply against current code, can you please check and resend?

A message that is not in the archive (sent off-list or not yet received): [email protected]

Axel Lin

author

2014-03-27 00:41 UTC #3 lore raw

2014-03-27 0:48 GMT+08:00 Mark Brown <[email protected]>:

Quoted 9 lines · Axel Lin

Quoted 5 lines
The correct way to set multiple bits settings is always clear these bit fields before set new settings.
Current code does not cause problem because the reset value of these bit fields are 0, and these settings only set once during probe.
This doesn't seem to apply against current code, can you please check and resend?

It's because v1 is applied.
I personally do not have strong preference between v1 and v2. Is it ok to keep it as is since it's applied.
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