linux-kernel - [PATCH v2 2/2] i2c:imx: Add an extra read at the end of an I2C slave read

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211112133956.655179-3-minyard@acm.org>
Date:   Fri, 12 Nov 2021 07:39:56 -0600
From:   minyard@....org
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Corey Minyard <minyard@....org>,
        Andrew Manley <andrew.manley@...lingtech.com>
Subject: [PATCH v2 2/2] i2c:imx: Add an extra read at the end of an I2C slave read

From: Corey Minyard <minyard@....org>

The I2C slave interface expects that the driver will read ahead one
byte.  The IMX driver/device doesn't do this, but simulate it so that
read operations get their index set correctly.

Signed-off-by: Corey Minyard <minyard@....org>
Tested-by: Andrew Manley <andrew.manley@...lingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@...lingtech.com>
Reviewed-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/i2c/busses/i2c-imx.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 27f969b3dc07..41355fc8bff4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -771,6 +771,15 @@ static irqreturn_t i2c_imx_slave_handle(struct imx_i2c_struct *i2c_imx,
 		ctl &= ~I2CR_MTX;
 		imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
 		imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+
+		/*
+		 * The i2c slave interface requires one extra dummy
+		 * read at the end to keep things in line.  See the
+		 * I2C slave docs for details.
+		 */
+		i2c_imx_slave_event(i2c_imx,
+				    I2C_SLAVE_READ_PROCESSED, &value);
+
 		i2c_imx_slave_finish_op(i2c_imx);
 		return IRQ_HANDLED;
 	}
-- 
2.25.1