Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933844AbcDEW0W (ORCPT ); Tue, 5 Apr 2016 18:26:22 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:36608 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933794AbcDEW0U (ORCPT ); Tue, 5 Apr 2016 18:26:20 -0400 Subject: Re: [PATCH 1/3] regulator: twl: Make sure we have access to powerbus before trying to write to it To: broonie@kernel.org References: <1458980895-10240-1-git-send-email-ivo.g.dimitrov.75@gmail.com> <1458980895-10240-2-git-send-email-ivo.g.dimitrov.75@gmail.com> Cc: tony@atomide.com, lgirdwood@gmail.com, sre@kernel.org, pali.rohar@gmail.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org From: Ivaylo Dimitrov Message-ID: <57043B87.20304@gmail.com> Date: Wed, 6 Apr 2016 01:26:15 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1458980895-10240-2-git-send-email-ivo.g.dimitrov.75@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3625 Lines: 128 On 26.03.2016 10:28, Ivaylo Dimitrov wrote: > According to the TRM, we need to enable i2c access to powerbus before > writing to it. Also, a new write to powerbus should not be attempted if > there is a pending transfer. The current code does not implement that > functionality and while there are no known problems caused by that, it is > better to follow what TRM says. > > Signed-off-by: Ivaylo Dimitrov > --- > drivers/regulator/twl-regulator.c | 78 +++++++++++++++++++++++++++++++++++---- > 1 file changed, 70 insertions(+), 8 deletions(-) > > diff --git a/drivers/regulator/twl-regulator.c b/drivers/regulator/twl-regulator.c > index 955a6fb..aad748b0 100644 > --- a/drivers/regulator/twl-regulator.c > +++ b/drivers/regulator/twl-regulator.c > @@ -21,7 +21,7 @@ > #include > #include > #include > - > +#include > > /* > * The TWL4030/TW5030/TPS659x0/TWL6030 family chips include power management, a > @@ -188,6 +188,74 @@ static int twl6030reg_is_enabled(struct regulator_dev *rdev) > return grp && (val == TWL6030_CFG_STATE_ON); > } > > +#define PB_I2C_BUSY BIT(0) > +#define PB_I2C_BWEN BIT(1) > + > +/* Wait until buffer empty/ready to send a word on power bus. */ > +static int twl4030_wait_pb_ready(void) > +{ > + > + int ret; > + int timeout = 10; > + u8 val; > + > + do { > + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val, > + TWL4030_PM_MASTER_PB_CFG); > + if (ret < 0) > + return ret; > + > + if (!(val & PB_I2C_BUSY)) > + return 0; > + > + mdelay(1); > + timeout--; > + } while (timeout); > + > + return -ETIMEDOUT; > +} > + > +/* Send a word over the powerbus */ > +static int twl4030_send_pb_msg(unsigned msg) > +{ > + u8 val; > + int ret; > + > + /* save powerbus configuration */ > + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val, > + TWL4030_PM_MASTER_PB_CFG); > + if (ret < 0) > + return ret; > + > + /* Enable i2c access to powerbus */ > + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val | PB_I2C_BWEN, > + TWL4030_PM_MASTER_PB_CFG); > + if (ret < 0) > + return ret; > + > + ret = twl4030_wait_pb_ready(); > + if (ret < 0) > + return ret; > + > + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg >> 8, > + TWL4030_PM_MASTER_PB_WORD_MSB); > + if (ret < 0) > + return ret; > + > + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg & 0xff, > + TWL4030_PM_MASTER_PB_WORD_LSB); > + if (ret < 0) > + return ret; > + > + ret = twl4030_wait_pb_ready(); > + if (ret < 0) > + return ret; > + > + /* Restore powerbus configuration */ > + return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val, > + TWL_MODULE_PM_MASTER); Hmm, I made a copy/paste error here, this should be: return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val, TWL4030_PM_MASTER_PB_CFG); Will send a new version of the patch. > +} > + > static int twl4030reg_enable(struct regulator_dev *rdev) > { > struct twlreg_info *info = rdev_get_drvdata(rdev); > @@ -324,13 +392,7 @@ static int twl4030reg_set_mode(struct regulator_dev *rdev, unsigned mode) > if (!(status & (P3_GRP_4030 | P2_GRP_4030 | P1_GRP_4030))) > return -EACCES; > > - status = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, > - message >> 8, TWL4030_PM_MASTER_PB_WORD_MSB); > - if (status < 0) > - return status; > - > - return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, > - message & 0xff, TWL4030_PM_MASTER_PB_WORD_LSB); > + return twl4030_send_pb_msg(message); > } > > static int twl6030reg_set_mode(struct regulator_dev *rdev, unsigned mode) > Ivo