From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Glauber Subject: [PATCH 3/4] i2c: octeon: thunderx: Limit register access retries Date: Fri, 9 Dec 2016 10:31:57 +0100 Message-ID: <20161209093158.3161-4-jglauber@cavium.com> References: <20161209093158.3161-1-jglauber@cavium.com> Return-path: Received: from mail-wm0-f67.google.com ([74.125.82.67]:32999 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933210AbcLIJca (ORCPT ); Fri, 9 Dec 2016 04:32:30 -0500 Received: by mail-wm0-f67.google.com with SMTP id u144so2764168wmu.0 for ; Fri, 09 Dec 2016 01:32:29 -0800 (PST) In-Reply-To: <20161209093158.3161-1-jglauber@cavium.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Wolfram Sang Cc: Paul Burton , "Steven J . Hill" , linux-i2c@vger.kernel.org, linux-mips@linux-mips.org, David Daney , Jan Glauber Do not infinitely retry register readq and writeq operations in order to not lock up the CPU in case the TWSI gets stuck. Return -EIO in case of a failed data read. For all other cases just return so subsequent operations will fail and trigger the recovery. Signed-off-by: Jan Glauber --- drivers/i2c/busses/i2c-octeon-core.c | 4 +++- drivers/i2c/busses/i2c-octeon-core.h | 21 ++++++++++++++++----- 2 files changed, 19 insertions(+), 6 deletions(-) diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c index 3d10f1a..1d8775799 100644 --- a/drivers/i2c/busses/i2c-octeon-core.c +++ b/drivers/i2c/busses/i2c-octeon-core.c @@ -342,7 +342,9 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target, if (result) return result; - data[i] = octeon_i2c_data_read(i2c); + data[i] = octeon_i2c_data_read(i2c, &result); + if (result) + return result; if (recv_len && i == 0) { if (data[i] > I2C_SMBUS_BLOCK_MAX + 1) return -EPROTO; diff --git a/drivers/i2c/busses/i2c-octeon-core.h b/drivers/i2c/busses/i2c-octeon-core.h index 87151ea..e160f83 100644 --- a/drivers/i2c/busses/i2c-octeon-core.h +++ b/drivers/i2c/busses/i2c-octeon-core.h @@ -141,11 +141,14 @@ static inline void octeon_i2c_writeq_flush(u64 val, void __iomem *addr) */ static inline void octeon_i2c_reg_write(struct octeon_i2c *i2c, u64 eop_reg, u8 data) { + int tries = 1000; u64 tmp; __raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI(i2c)); do { tmp = __raw_readq(i2c->twsi_base + SW_TWSI(i2c)); + if (--tries < 0) + return; } while ((tmp & SW_TWSI_V) != 0); } @@ -163,24 +166,32 @@ static inline void octeon_i2c_reg_write(struct octeon_i2c *i2c, u64 eop_reg, u8 * * The I2C core registers are accessed indirectly via the SW_TWSI CSR. */ -static inline u8 octeon_i2c_reg_read(struct octeon_i2c *i2c, u64 eop_reg) +static inline int octeon_i2c_reg_read(struct octeon_i2c *i2c, u64 eop_reg, + int *error) { + int tries = 1000; u64 tmp; __raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI(i2c)); do { tmp = __raw_readq(i2c->twsi_base + SW_TWSI(i2c)); + if (--tries < 0) { + /* signal that the returned data is invalid */ + if (error) + *error = -EIO; + return 0; + } } while ((tmp & SW_TWSI_V) != 0); return tmp & 0xFF; } #define octeon_i2c_ctl_read(i2c) \ - octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_CTL) -#define octeon_i2c_data_read(i2c) \ - octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_DATA) + octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_CTL, NULL) +#define octeon_i2c_data_read(i2c, error) \ + octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_DATA, error) #define octeon_i2c_stat_read(i2c) \ - octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_STAT) + octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_STAT, NULL) /** * octeon_i2c_read_int - read the TWSI_INT register -- 2.9.0.rc0.21.g7777322