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Wed, 09 Sep 2020 09:59:17 -0700 (PDT) Date: Wed, 9 Sep 2020 19:59:15 +0300 From: Cristian Ciocaltea To: Manivannan Sadhasivam Subject: Re: [PATCH v2 1/1] i2c: busses: Add support for atomic transfers in Actions Semi Owl driver Message-ID: <20200909165915.GA387239@BV030612LT> References: <20200909151748.GA11397@mani> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200909151748.GA11397@mani> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200909_125919_811265_9535F62D X-CRM114-Status: GOOD ( 37.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-actions@lists.infradead.org, Andreas =?iso-8859-1?Q?F=E4rber?= , linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mani, Thanks for the review! On Wed, Sep 09, 2020 at 08:47:48PM +0530, Manivannan Sadhasivam wrote: > Hi Cristi, > > On 0908, Cristian Ciocaltea wrote: > > Atomic transfers are required to properly power off a machine through > > an I2C controlled PMIC, such as the Actions Semi ATC260x series. > > > > System shutdown may happen with interrupts being disabled and, as a > > consequence, the kernel may hang if the driver does not support atomic > > transfers. > > > > This functionality is essentially implemented by polling the FIFO > > Status register until either Command Execute Completed or NACK Error > > bits are set. > > > > Thanks for the patch! I just have couple of minor comments and other > than that it looks good to me. > > > Signed-off-by: Cristian Ciocaltea > > --- > > Changes in v2: > > - Dropped unused return codes from owl_i2c_xfer_data(), per Mani's review > > - Rebased patch on v5.9-rc4 > > > > drivers/i2c/busses/i2c-owl.c | 78 ++++++++++++++++++++++++++---------- > > 1 file changed, 57 insertions(+), 21 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-owl.c b/drivers/i2c/busses/i2c-owl.c > > index 672f1f239bd6..29605257831f 100644 > > --- a/drivers/i2c/busses/i2c-owl.c > > +++ b/drivers/i2c/busses/i2c-owl.c > > @@ -14,6 +14,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > > > @@ -76,6 +77,7 @@ > > #define OWL_I2C_FIFOCTL_TFR BIT(2) > > > > /* I2Cc_FIFOSTAT Bit Mask */ > > +#define OWL_I2C_FIFOSTAT_CECB BIT(0) > > #define OWL_I2C_FIFOSTAT_RNB BIT(1) > > #define OWL_I2C_FIFOSTAT_RFE BIT(2) > > #define OWL_I2C_FIFOSTAT_TFF BIT(5) > > @@ -83,7 +85,8 @@ > > #define OWL_I2C_FIFOSTAT_RFD GENMASK(15, 8) > > > > /* I2C bus timeout */ > > -#define OWL_I2C_TIMEOUT msecs_to_jiffies(4 * 1000) > > +#define OWL_I2C_TIMEOUT_MS (4 * 1000) > > +#define OWL_I2C_TIMEOUT msecs_to_jiffies(OWL_I2C_TIMEOUT_MS) > > > > #define OWL_I2C_MAX_RETRIES 50 > > > > @@ -161,29 +164,25 @@ static void owl_i2c_set_freq(struct owl_i2c_dev *i2c_dev) > > writel(OWL_I2C_DIV_FACTOR(val), i2c_dev->base + OWL_I2C_REG_CLKDIV); > > } > > > > -static irqreturn_t owl_i2c_interrupt(int irq, void *_dev) > > +static void owl_i2c_xfer_data(struct owl_i2c_dev *i2c_dev) > > { > > - struct owl_i2c_dev *i2c_dev = _dev; > > struct i2c_msg *msg = i2c_dev->msg; > > - unsigned long flags; > > unsigned int stat, fifostat; > > > > - spin_lock_irqsave(&i2c_dev->lock, flags); > > - > > i2c_dev->err = 0; > > > > /* Handle NACK from slave */ > > fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT); > > if (fifostat & OWL_I2C_FIFOSTAT_RNB) { > > i2c_dev->err = -ENXIO; > > - goto stop; > > + return; > > } > > > > /* Handle bus error */ > > stat = readl(i2c_dev->base + OWL_I2C_REG_STAT); > > if (stat & OWL_I2C_STAT_BEB) { > > i2c_dev->err = -EIO; > > - goto stop; > > + return; > > } > > > > /* Handle FIFO read */ > > @@ -196,18 +195,28 @@ static irqreturn_t owl_i2c_interrupt(int irq, void *_dev) > > } else { > > /* Handle the remaining bytes which were not sent */ > > while (!(readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) & > > - OWL_I2C_FIFOSTAT_TFF) && i2c_dev->msg_ptr < msg->len) { > > + OWL_I2C_FIFOSTAT_TFF) && i2c_dev->msg_ptr < msg->len) { > > Spurious change? I have just fixed a small indentation issue (removed extra space char in front of OWL_I2C...). I will revert it if you think it's not the right context for doing this (located ~10 lines bellow the previous edit). > > writel(msg->buf[i2c_dev->msg_ptr++], > > i2c_dev->base + OWL_I2C_REG_TXDAT); > > } > > } > > +} > > + > > +static irqreturn_t owl_i2c_interrupt(int irq, void *_dev) > > +{ > > + struct owl_i2c_dev *i2c_dev = _dev; > > + unsigned long flags; > > + > > + spin_lock_irqsave(&i2c_dev->lock, flags); > > + > > + owl_i2c_xfer_data(i2c_dev); > > > > -stop: > > /* Clear pending interrupts */ > > owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT, > > OWL_I2C_STAT_IRQP, true); > > > > complete_all(&i2c_dev->msg_complete); > > + > > spin_unlock_irqrestore(&i2c_dev->lock, flags); > > > > return IRQ_HANDLED; > > @@ -235,8 +244,8 @@ static int owl_i2c_check_bus_busy(struct i2c_adapter *adap) > > return 0; > > } > > > > -static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > > - int num) > > +static int owl_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg *msgs, > > + int num, bool atomic) > > { > > struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap); > > struct i2c_msg *msg; > > @@ -280,11 +289,12 @@ static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > > goto err_exit; > > } > > > > - reinit_completion(&i2c_dev->msg_complete); > > + if (!atomic) > > + reinit_completion(&i2c_dev->msg_complete); > > > > - /* Enable I2C controller interrupt */ > > + /* Enable/disable I2C controller interrupt */ > > owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL, > > - OWL_I2C_CTL_IRQE, true); > > + OWL_I2C_CTL_IRQE, !atomic); > > > > /* > > * Select: FIFO enable, Master mode, Stop enable, Data count enable, > > @@ -352,20 +362,33 @@ static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > > > > spin_unlock_irqrestore(&i2c_dev->lock, flags); > > > > - time_left = wait_for_completion_timeout(&i2c_dev->msg_complete, > > - adap->timeout); > > + if (atomic) { > > + /* Wait for Command Execute Completed or NACK Error bits */ > > + ret = readl_poll_timeout_atomic(i2c_dev->base + OWL_I2C_REG_FIFOSTAT, > > + val, val & (OWL_I2C_FIFOSTAT_CECB | > > + OWL_I2C_FIFOSTAT_RNB), > > + 10, OWL_I2C_TIMEOUT_MS * 1000); > > + } else { > > + time_left = wait_for_completion_timeout(&i2c_dev->msg_complete, > > + adap->timeout); > > + if (!time_left) > > + ret = -ETIMEDOUT; > > + } > > > > spin_lock_irqsave(&i2c_dev->lock, flags); > > - if (time_left == 0) { > > + > > + if (ret) { > > dev_err(&adap->dev, "Transaction timed out\n"); > > /* Send stop condition and release the bus */ > > owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL, > > OWL_I2C_CTL_GBCC_STOP | OWL_I2C_CTL_RB, > > true); > > - ret = -ETIMEDOUT; > > goto err_exit; > > } > > > > + if (atomic) > > + owl_i2c_xfer_data(i2c_dev); > > You are not clearing the pending interrupts here. I assumed this is not needed for atomic contexts since the controller interrupt is disabled (please see the comment above: Enable/disable I2C controller interrupt). Otherwise I will simply move the clear pending interrupts code from owl_i2c_interrupt() to owl_i2c_xfer_data(). > Thanks, > Mani > > > + > > ret = i2c_dev->err < 0 ? i2c_dev->err : num; > > > > err_exit: > > @@ -379,9 +402,22 @@ static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > > return ret; > > } > > > > +static int owl_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > > + int num) > > +{ > > + return owl_i2c_xfer_common(adap, msgs, num, false); > > +} > > + > > +static int owl_i2c_xfer_atomic(struct i2c_adapter *adap, > > + struct i2c_msg *msgs, int num) > > +{ > > + return owl_i2c_xfer_common(adap, msgs, num, true); > > +} > > + > > static const struct i2c_algorithm owl_i2c_algorithm = { > > - .master_xfer = owl_i2c_master_xfer, > > - .functionality = owl_i2c_func, > > + .master_xfer = owl_i2c_xfer, > > + .master_xfer_atomic = owl_i2c_xfer_atomic, > > + .functionality = owl_i2c_func, > > }; > > > > static const struct i2c_adapter_quirks owl_i2c_quirks = { > > -- > > 2.28.0 > > Kind regards, Cristi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel