linux-kernel - [PATCH v1] I2C Designware Core Supports SMBUS BLOCK

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Date:   Tue, 25 Oct 2016 11:35:13 +0700
From:   tnhuynh@....com
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Loc Ho <lho@....com>, Thang Nguyen <tqnguyen@....com>,
        Phong Vo <pvo@....com>, patches@....com,
        Tin Huynh <tnhuynh@....com>
Subject: [PATCH v1] I2C Designware Core Supports SMBUS BLOCK

From: Tin Huynh <tnhuynh@....com>

Free and Open IPMI use SMBUS BLOCK Read/Write to support SSIF protocol.
However, I2C Designwave Core Driver doesn't handle the case at the moment.
The below patch supports this feature.

Signed-off-by: Tin Huynh <tnhuynh@....com>
---
 drivers/i2c/busses/i2c-designware-core.c    |   42 +++++++++++++++++++++++++--
 drivers/i2c/busses/i2c-designware-platdrv.c |    1 +
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 1fe93c4..3abf0e5 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -588,8 +588,17 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 			 * detected from the registers so we set it always
 			 * when writing/reading the last byte.
 			 */
+
+			/*
+			 * i2c-core.c always set the buffer length of
+			 * I2C_FUNC_SMBUS_BLOCK_DATA to 1. The length will
+			 * be adjusted when receiving the first byte.
+			 * Thus we can't stop the transaction here.
+			 */
+
 			if (dev->msg_write_idx == dev->msgs_num - 1 &&
-			    buf_len == 1)
+			    buf_len == 1 &&
+			    !(msgs[dev->msg_write_idx].flags & I2C_M_RECV_LEN))
 				cmd |= BIT(9);
 
 			if (need_restart) {
@@ -614,7 +623,14 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 		dev->tx_buf = buf;
 		dev->tx_buf_len = buf_len;
 
-		if (buf_len > 0) {
+		/*
+		 * Because we don't know the buffer length in the
+		 * I2C_FUNC_SMBUS_BLOCK_DATA case, we can't stop
+		 * the transcation here.
+		 */
+
+		if (buf_len > 0 ||
+			msgs[dev->msg_write_idx].flags & I2C_M_RECV_LEN) {
 			/* more bytes to be written */
 			dev->status |= STATUS_WRITE_IN_PROGRESS;
 			break;
@@ -659,7 +675,27 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 		rx_valid = dw_readl(dev, DW_IC_RXFLR);
 
 		for (; len > 0 && rx_valid > 0; len--, rx_valid--) {
-			*buf++ = dw_readl(dev, DW_IC_DATA_CMD);
+			*buf = dw_readl(dev, DW_IC_DATA_CMD);
+			/* ensure length byte is a valid value */
+			if (msgs[dev->msg_read_idx].flags & I2C_M_RECV_LEN
+				&& *buf <= I2C_SMBUS_BLOCK_MAX  && *buf > 0) {
+				/*
+				 * Adjust the buffer length and mask the flag
+				 * after receiving the first byte
+				 */
+				msgs[dev->msg_read_idx].flags &=
+								~I2C_M_RECV_LEN;
+				len = *buf + 1;
+				/* Increase one with PEC flag */
+				if (msgs[dev->msg_read_idx].flags &
+							I2C_CLIENT_PEC)
+					len++;
+
+				dev->tx_buf_len = len > dev->rx_outstanding ?
+					len - dev->rx_outstanding : 0;
+				msgs[dev->msg_read_idx].len = len;
+			}
+			buf++;
 			dev->rx_outstanding--;
 		}
 
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 0b42a12..886fb62 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -220,6 +220,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 		I2C_FUNC_SMBUS_BYTE |
 		I2C_FUNC_SMBUS_BYTE_DATA |
 		I2C_FUNC_SMBUS_WORD_DATA |
+		I2C_FUNC_SMBUS_BLOCK_DATA |
 		I2C_FUNC_SMBUS_I2C_BLOCK;
 
 	dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
-- 
1.7.1


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