[PATCH 1/5] i2c: qcom-cci: Factor out write command queue programming

[Loic Poulain <loic.poulain@oss.qualcomm.com>]

Factor out write-command queueing into a dedicated helper and replace
the manual byte-to-word packing code with iowrite32_rep().
 
The resulting code is easier to follow and will be reused by
upcoming burst-write support.

Also add a sanity check on the write buffer length, which should
already be validated by the caller/I2C-core.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-qcom-cci.c | 41 +++++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
index 526a699eee147996b2756b47c0e6982678990be0..c4bb97868c54de636be756328ca7ee4e46e6b400 100644
--- a/drivers/i2c/busses/i2c-qcom-cci.c
+++ b/drivers/i2c/busses/i2c-qcom-cci.c
@@ -77,6 +77,9 @@
 #define CCI_I2C_WRITE		9
 #define CCI_I2C_READ		10
 
+#define CCI_I2C_WRITE_WC	3
+#define CCI_I2C_WRITE_NWORDS(len) DIV_ROUND_UP((len) + 1, sizeof(u32))
+
 #define CCI_I2C_REPORT_IRQ_EN	BIT(8)
 
 enum {
@@ -485,42 +488,42 @@ static int cci_i2c_read(struct cci *cci, u16 master,
 	return 0;
 }
 
+static void cci_i2c_load_write(u8 *buf, u16 len, void __iomem *loadq)
+{
+	u32 cmd[CCI_I2C_WRITE_WC] = { };
+
+	if (WARN_ON(len >= CCI_I2C_WRITE_WC * sizeof(u32)))
+		return;
+
+	cmd[0] = CCI_I2C_WRITE | len << 4;
+	memcpy((u8 *)cmd + 1, buf, len);
+	iowrite32_rep(loadq, cmd, CCI_I2C_WRITE_NWORDS(len));
+}
+
 static int cci_i2c_write(struct cci *cci, u16 master,
 			 u16 addr, u8 *buf, u16 len)
 {
-	u8 queue = QUEUE_0;
-	u8 load[12] = { 0 };
-	int i = 0, j, ret;
+	void __iomem *loadq = cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, QUEUE_0);
+	int ret;
 	u32 val;
 
 	/*
 	 * Call validate queue to make sure queue is empty before starting.
 	 * This is to avoid overflow / underflow of queue.
 	 */
-	ret = cci_validate_queue(cci, master, queue);
+	ret = cci_validate_queue(cci, master, QUEUE_0);
 	if (ret < 0)
 		return ret;
 
 	val = CCI_I2C_SET_PARAM | (addr & 0x7f) << 4;
-	writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
+	writel(val, loadq);
 
-	load[i++] = CCI_I2C_WRITE | len << 4;
-
-	for (j = 0; j < len; j++)
-		load[i++] = buf[j];
-
-	for (j = 0; j < i; j += 4) {
-		val = load[j];
-		val |= load[j + 1] << 8;
-		val |= load[j + 2] << 16;
-		val |= load[j + 3] << 24;
-		writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
-	}
+	cci_i2c_load_write(buf, len, loadq);
 
 	val = CCI_I2C_REPORT | CCI_I2C_REPORT_IRQ_EN;
-	writel(val, cci->base + CCI_I2C_Mm_Qn_LOAD_DATA(master, queue));
+	writel(val, loadq);
 
-	return cci_run_queue(cci, master, queue);
+	return cci_run_queue(cci, master, QUEUE_0);
 }
 
 static int cci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)

-- 
2.34.1