Re: [PATCH v4 2/2] i2c: stm32f7: add SMBus-Alert support

Pierre Yves MORDRET
2021-05-10T08:05:34Z

Hi all

Look good to me. I agree more generic

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>

Regards

On 5/5/21 3:14 PM, Alain Volmat wrote:
> Add support for the SMBus-Alert protocol to the STM32F7 that has
> dedicated control and status logic.
>
> If SMBus-Alert is used, the SMBALERT# pin must be configured as alternate
> function for I2C Alert.
>
> Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
> ---
> v4: - check for smbus-alert property
> v2: - rely on st,smbus-alert binding instead of smbus
> ---
> drivers/i2c/busses/i2c-stm32f7.c | 73 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 73 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index 0138317ea600..b9b19a2a2ffa 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -51,6 +51,7 @@
>
> /* STM32F7 I2C control 1 */
> #define STM32F7_I2C_CR1_PECEN BIT(23)
> +#define STM32F7_I2C_CR1_ALERTEN BIT(22)
> #define STM32F7_I2C_CR1_SMBHEN BIT(20)
> #define STM32F7_I2C_CR1_WUPEN BIT(18)
> #define STM32F7_I2C_CR1_SBC BIT(16)
> @@ -125,6 +126,7 @@
> (((n) & STM32F7_I2C_ISR_ADDCODE_MASK) >> 17)
> #define STM32F7_I2C_ISR_DIR BIT(16)
> #define STM32F7_I2C_ISR_BUSY BIT(15)
> +#define STM32F7_I2C_ISR_ALERT BIT(13)
> #define STM32F7_I2C_ISR_PECERR BIT(11)
> #define STM32F7_I2C_ISR_ARLO BIT(9)
> #define STM32F7_I2C_ISR_BERR BIT(8)
> @@ -138,6 +140,7 @@
> #define STM32F7_I2C_ISR_TXE BIT(0)
>
> /* STM32F7 I2C Interrupt Clear */
> +#define STM32F7_I2C_ICR_ALERTCF BIT(13)
> #define STM32F7_I2C_ICR_PECCF BIT(11)
> #define STM32F7_I2C_ICR_ARLOCF BIT(9)
> #define STM32F7_I2C_ICR_BERRCF BIT(8)
> @@ -279,6 +282,17 @@ struct stm32f7_i2c_msg {
> };
>
> /**
> + * struct stm32f7_i2c_alert - SMBus alert specific data
> + * @setup: platform data for the smbus_alert i2c client
> + * @ara: I2C slave device used to respond to the SMBus Alert with Alert
> + * Response Address
> + */
> +struct stm32f7_i2c_alert {
> + struct i2c_smbus_alert_setup setup;
> + struct i2c_client *ara;
> +};
> +
> +/**
> * struct stm32f7_i2c_dev - private data of the controller
> * @adap: I2C adapter for this controller
> * @dev: device for this controller
> @@ -310,6 +324,7 @@ struct stm32f7_i2c_msg {
> * @analog_filter: boolean to indicate enabling of the analog filter
> * @dnf_dt: value of digital filter requested via dt
> * @dnf: value of digital filter to apply
> + * @alert: SMBus alert specific data
> */
> struct stm32f7_i2c_dev {
> struct i2c_adapter adap;
> @@ -341,6 +356,7 @@ struct stm32f7_i2c_dev {
> bool analog_filter;
> u32 dnf_dt;
> u32 dnf;
> + struct stm32f7_i2c_alert *alert;
> };
>
> /*
> @@ -1624,6 +1640,13 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
> f7_msg->result = -EINVAL;
> }
>
> + if (status & STM32F7_I2C_ISR_ALERT) {
> + dev_dbg(dev, "<%s>: SMBus alert received\n", __func__);
> + writel_relaxed(STM32F7_I2C_ICR_ALERTCF, base + STM32F7_I2C_ICR);
> + i2c_handle_smbus_alert(i2c_dev->alert->ara);
> + return IRQ_HANDLED;
> + }
> +
> if (!i2c_dev->slave_running) {
> u32 mask;
> /* Disable interrupts */
> @@ -1990,6 +2013,42 @@ static void stm32f7_i2c_disable_smbus_host(struct stm32f7_i2c_dev *i2c_dev)
> }
> }
>
> +static int stm32f7_i2c_enable_smbus_alert(struct stm32f7_i2c_dev *i2c_dev)
> +{
> + struct stm32f7_i2c_alert *alert;
> + struct i2c_adapter *adap = &i2c_dev->adap;
> + struct device *dev = i2c_dev->dev;
> + void __iomem *base = i2c_dev->base;
> +
> + alert = devm_kzalloc(dev, sizeof(*alert), GFP_KERNEL);
> + if (!alert)
> + return -ENOMEM;
> +
> + alert->ara = i2c_new_smbus_alert_device(adap, &alert->setup);
> + if (IS_ERR(alert->ara))
> + return PTR_ERR(alert->ara);
> +
> + i2c_dev->alert = alert;
> +
> + /* Enable SMBus Alert */
> + stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, STM32F7_I2C_CR1_ALERTEN);
> +
> + return 0;
> +}
> +
> +static void stm32f7_i2c_disable_smbus_alert(struct stm32f7_i2c_dev *i2c_dev)
> +{
> + struct stm32f7_i2c_alert *alert = i2c_dev->alert;
> + void __iomem *base = i2c_dev->base;
> +
> + if (alert) {
> + /* Disable SMBus Alert */
> + stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1,
> + STM32F7_I2C_CR1_ALERTEN);
> + i2c_unregister_device(alert->ara);
> + }
> +}
> +
> static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
> {
> struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> @@ -2173,6 +2232,16 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
> }
> }
>
> + if (of_property_read_bool(pdev->dev.of_node, "smbus-alert")) {
> + ret = stm32f7_i2c_enable_smbus_alert(i2c_dev);
> + if (ret) {
> + dev_err(i2c_dev->dev,
> + "failed to enable SMBus alert protocol (%d)\n",
> + ret);
> + goto i2c_disable_smbus_host;
> + }
> + }
> +
> dev_info(i2c_dev->dev, "STM32F7 I2C-%d bus adapter\n", adap->nr);
>
> pm_runtime_mark_last_busy(i2c_dev->dev);
> @@ -2180,6 +2249,9 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>
> return 0;
>
> +i2c_disable_smbus_host:
> + stm32f7_i2c_disable_smbus_host(i2c_dev);
> +
> i2c_adapter_remove:
> i2c_del_adapter(adap);
>
> @@ -2214,6 +2286,7 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
> {
> struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
>
> + stm32f7_i2c_disable_smbus_alert(i2c_dev);
> stm32f7_i2c_disable_smbus_host(i2c_dev);
>
> i2c_del_adapter(&i2c_dev->adap);
>

--
--
~ Py MORDRET