mtd: spi-nor: Pointer parameter for SR in spi_nor_read_sr()

Let the callers pass the pointer to the DMA-able buffer where
the value of the Status Register will be written. This way we
avoid the casts between int and u8, which can be confusing.

Callers stop compare the return value of spi_nor_read_sr() with negative,
spi_nor_read_sr() returns 0 on success and -errno otherwise.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

drivers/mtd/spi-nor/spi-nor.c

@@ -425,12 +425,15 @@ static int spi_nor_write_disable(struct spi_nor *nor)
 	return nor->controller_ops->write_reg(nor, SPINOR_OP_WRDI, NULL, 0);
 }
 
-/*
- * Read the status register, returning its value in the location
- * Return the status register value.
- * Returns negative if error occurred.
+/**
+ * spi_nor_read_sr() - Read the Status Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr:		pointer to a DMA-able buffer where the value of the
+ *              Status Register will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_read_sr(struct spi_nor *nor)
+static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
 {
 	int ret;
 
@@ -439,20 +442,18 @@ static int spi_nor_read_sr(struct spi_nor *nor)
 			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
+				   SPI_MEM_OP_DATA_IN(1, sr, 1));
 
 		ret = spi_mem_exec_op(nor->spimem, &op);
 	} else {
 		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDSR,
-						    nor->bouncebuf, 1);
+						    sr, 1);
 	}
 
-	if (ret) {
+	if (ret)
 		pr_err("error %d reading SR\n", ret);
-		return ret;
-	}
 
-	return nor->bouncebuf[0];
+	return ret;
 }
 
 /*
@@ -668,12 +669,14 @@ static int spi_nor_clear_sr(struct spi_nor *nor)
 
 static int spi_nor_sr_ready(struct spi_nor *nor)
 {
-	int sr = spi_nor_read_sr(nor);
-	if (sr < 0)
-		return sr;
+	int ret = spi_nor_read_sr(nor, nor->bouncebuf);
+
+	if (ret)
+		return ret;
 
-	if (nor->flags & SNOR_F_USE_CLSR && sr & (SR_E_ERR | SR_P_ERR)) {
-		if (sr & SR_E_ERR)
+	if (nor->flags & SNOR_F_USE_CLSR &&
+	    nor->bouncebuf[0] & (SR_E_ERR | SR_P_ERR)) {
+		if (nor->bouncebuf[0] & SR_E_ERR)
 			dev_err(nor->dev, "Erase Error occurred\n");
 		else
 			dev_err(nor->dev, "Programming Error occurred\n");
@@ -682,7 +685,7 @@ static int spi_nor_sr_ready(struct spi_nor *nor)
 		return -EIO;
 	}
 
-	return !(sr & SR_WIP);
+	return !(nor->bouncebuf[0] & SR_WIP);
 }
 
 static int spi_nor_clear_fsr(struct spi_nor *nor)
@@ -831,11 +834,11 @@ static int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 status_new,
 	if (ret)
 		return ret;
 
-	ret = spi_nor_read_sr(nor);
-	if (ret < 0)
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
 		return ret;
 
-	return ((ret & mask) != (status_new & mask)) ? -EIO : 0;
+	return ((nor->bouncebuf[0] & mask) != (status_new & mask)) ? -EIO : 0;
 }
 
 static int spi_nor_write_sr2(struct spi_nor *nor, u8 *sr2)
@@ -1510,16 +1513,18 @@ static int stm_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
 static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
-	int status_old, status_new;
+	int ret, status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 shift = ffs(mask) - 1, pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
 
-	status_old = spi_nor_read_sr(nor);
-	if (status_old < 0)
-		return status_old;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	status_old = nor->bouncebuf[0];
 
 	/* If nothing in our range is unlocked, we don't need to do anything */
 	if (stm_is_locked_sr(nor, ofs, len, status_old))
@@ -1590,16 +1595,18 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
-	int status_old, status_new;
+	int ret, status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 shift = ffs(mask) - 1, pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
 
-	status_old = spi_nor_read_sr(nor);
-	if (status_old < 0)
-		return status_old;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	status_old = nor->bouncebuf[0];
 
 	/* If nothing in our range is locked, we don't need to do anything */
 	if (stm_is_unlocked_sr(nor, ofs, len, status_old))
@@ -1674,13 +1681,13 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
  */
 static int stm_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
-	int status;
+	int ret;
 
-	status = spi_nor_read_sr(nor);
-	if (status < 0)
-		return status;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
 
-	return stm_is_locked_sr(nor, ofs, len, status);
+	return stm_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
 }
 
 static const struct spi_nor_locking_ops stm_locking_ops = {
@@ -1746,24 +1753,28 @@ static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
  */
 static int macronix_quad_enable(struct spi_nor *nor)
 {
-	int ret, val;
+	int ret;
+
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
 
-	val = spi_nor_read_sr(nor);
-	if (val < 0)
-		return val;
-	if (val & SR_QUAD_EN_MX)
+	if (nor->bouncebuf[0] & SR_QUAD_EN_MX)
 		return 0;
 
 	spi_nor_write_enable(nor);
 
-	spi_nor_write_sr(nor, val | SR_QUAD_EN_MX);
+	spi_nor_write_sr(nor, nor->bouncebuf[0] | SR_QUAD_EN_MX);
 
 	ret = spi_nor_wait_till_ready(nor);
 	if (ret)
 		return ret;
 
-	ret = spi_nor_read_sr(nor);
-	if (!(ret > 0 && (ret & SR_QUAD_EN_MX))) {
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	if (!(nor->bouncebuf[0] & SR_QUAD_EN_MX)) {
 		dev_err(nor->dev, "Macronix Quad bit not set\n");
 		return -EINVAL;
 	}
@@ -1835,12 +1846,12 @@ static int spansion_no_read_cr_quad_enable(struct spi_nor *nor)
 	int ret;
 
 	/* Keep the current value of the Status Register. */
-	ret = spi_nor_read_sr(nor);
-	if (ret < 0) {
+	ret = spi_nor_read_sr(nor, sr_cr);
+	if (ret) {
 		dev_err(nor->dev, "error while reading status register\n");
 		return ret;
 	}
-	sr_cr[0] = ret;
+
 	sr_cr[1] = CR_QUAD_EN_SPAN;
 
 	return spi_nor_write_sr_cr(nor, sr_cr);
@@ -1878,12 +1889,11 @@ static int spansion_read_cr_quad_enable(struct spi_nor *nor)
 	sr_cr[1] = ret | CR_QUAD_EN_SPAN;
 
 	/* Keep the current value of the Status Register. */
-	ret = spi_nor_read_sr(nor);
-	if (ret < 0) {
+	ret = spi_nor_read_sr(nor, sr_cr);
+	if (ret) {
 		dev_err(dev, "error while reading status register\n");
 		return ret;
 	}
-	sr_cr[0] = ret;
 
 	ret = spi_nor_write_sr_cr(nor, sr_cr);
 	if (ret)
@@ -1967,15 +1977,15 @@ static int spi_nor_clear_sr_bp(struct spi_nor *nor)
 	int ret;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 
-	ret = spi_nor_read_sr(nor);
-	if (ret < 0) {
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret) {
 		dev_err(nor->dev, "error while reading status register\n");
 		return ret;
 	}
 
 	spi_nor_write_enable(nor);
 
-	ret = spi_nor_write_sr(nor, ret & ~mask);
+	ret = spi_nor_write_sr(nor, nor->bouncebuf[0] & ~mask);
 	if (ret) {
 		dev_err(nor->dev, "write to status register failed\n");
 		return ret;
@@ -2021,13 +2031,14 @@ static int spi_nor_spansion_clear_sr_bp(struct spi_nor *nor)
 	if (ret & CR_QUAD_EN_SPAN) {
 		sr_cr[1] = ret;
 
-		ret = spi_nor_read_sr(nor);
-		if (ret < 0) {
+		ret = spi_nor_read_sr(nor, sr_cr);
+		if (ret) {
 			dev_err(nor->dev,
 				"error while reading status register\n");
 			return ret;
 		}
-		sr_cr[0] = ret & ~mask;
+
+		sr_cr[0] &= ~mask;
 
 		ret = spi_nor_write_sr_cr(nor, sr_cr);
 		if (ret)