From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out001.atlarge.net (out001.atlarge.net [129.41.63.69]) by ozlabs.org (Postfix) with ESMTP id A3232DDF10 for ; Mon, 9 Jul 2007 17:19:59 +1000 (EST) Date: Mon, 9 Jul 2007 09:19:55 +0200 From: Domen Puncer To: khali@linux-fr.org Subject: [PATCH] i2c-mpc: work around missing-9th-clock-pulse bug Message-ID: <20070709071955.GD4186@moe.telargo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: i2c@lm-sensors.org, linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Work around a problem reported on: http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html Without this patch I2C on mpc5200 becomes unusable after a while. Tested on mpc5200 based boards by Matthias and me. Signed-off-by: Domen Puncer --- drivers/i2c/busses/i2c-mpc.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) Index: work-powerpc.git/drivers/i2c/busses/i2c-mpc.c =================================================================== --- work-powerpc.git.orig/drivers/i2c/busses/i2c-mpc.c +++ work-powerpc.git/drivers/i2c/busses/i2c-mpc.c @@ -74,6 +74,20 @@ static irqreturn_t mpc_i2c_isr(int irq, return IRQ_HANDLED; } +static void mpc_i2c_fixup(struct mpc_i2c *i2c) +{ + writeccr(i2c, 0); + udelay(30); + writeccr(i2c, CCR_MEN); + udelay(30); + writeccr(i2c, CCR_MSTA | CCR_MTX); + udelay(30); + writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN); + udelay(30); + writeccr(i2c, CCR_MEN); + udelay(30); +} + static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing) { unsigned long orig_jiffies = jiffies; @@ -153,6 +167,9 @@ static void mpc_i2c_start(struct mpc_i2c static void mpc_i2c_stop(struct mpc_i2c *i2c) { writeccr(i2c, CCR_MEN); + mb(); + writeccr(i2c, 0); + mb(); } static int mpc_write(struct mpc_i2c *i2c, int target, @@ -245,6 +262,8 @@ static int mpc_xfer(struct i2c_adapter * } if (time_after(jiffies, orig_jiffies + HZ)) { pr_debug("I2C: timeout\n"); + if (readb(i2c->base + MPC_I2C_SR) == (CSR_MCF | CSR_MBB | CSR_RXAK)) + mpc_i2c_fixup(i2c); return -EIO; } schedule();