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Subject: Re: [PATCH v3 2/2] i2c: stm32f7: Add SMBus Host-Notify protocol
 support
To:     Alain Volmat <alain.volmat@st.com>, <wsa@kernel.org>
CC:     <alexandre.torgue@st.com>, <linux-i2c@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <fabrice.gasnier@st.com>
References: <1596431876-24115-1-git-send-email-alain.volmat@st.com>
 <1596431876-24115-3-git-send-email-alain.volmat@st.com>
From:   Pierre Yves MORDRET <pierre-yves.mordret@st.com>
Message-ID: <e27abfbc-6cb4-ab00-04ea-4147982c8393@st.com>
Date:   Tue, 4 Aug 2020 16:04:28 +0200
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Hi Alain

Look good for me

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

Best Regards

On 8/3/20 7:17 AM, Alain Volmat wrote:
> Rely on the core functions to implement the host-notify
> protocol via the a I2C slave device.
> 
> Signed-off-by: Alain Volmat <alain.volmat@st.com>
> ---
>  v3: identical to v2
>  v2: fix slot #0 usage condition within stm32f7_i2c_get_free_slave_id
> 
>  drivers/i2c/busses/Kconfig       |   1 +
>  drivers/i2c/busses/i2c-stm32f7.c | 110 +++++++++++++++++++++++++++++++++------
>  2 files changed, 96 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 735bf31a3fdf..ae8671727a4c 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1036,6 +1036,7 @@ config I2C_STM32F7
>  	tristate "STMicroelectronics STM32F7 I2C support"
>  	depends on ARCH_STM32 || COMPILE_TEST
>  	select I2C_SLAVE
> +	select I2C_SMBUS
>  	help
>  	  Enable this option to add support for STM32 I2C controller embedded
>  	  in STM32F7 SoCs.
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index bff3479fe122..223c238c3c09 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -18,6 +18,7 @@
>  #include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/i2c.h>
> +#include <linux/i2c-smbus.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
> @@ -50,6 +51,7 @@
>  
>  /* STM32F7 I2C control 1 */
>  #define STM32F7_I2C_CR1_PECEN			BIT(23)
> +#define STM32F7_I2C_CR1_SMBHEN			BIT(20)
>  #define STM32F7_I2C_CR1_WUPEN			BIT(18)
>  #define STM32F7_I2C_CR1_SBC			BIT(16)
>  #define STM32F7_I2C_CR1_RXDMAEN			BIT(15)
> @@ -150,7 +152,7 @@
>  
>  #define STM32F7_I2C_MAX_LEN			0xff
>  #define STM32F7_I2C_DMA_LEN_MIN			0x16
> -#define STM32F7_I2C_MAX_SLAVE			0x2
> +#define STM32F7_I2C_MAX_SLAVE			0x3
>  
>  #define STM32F7_I2C_DNF_DEFAULT			0
>  #define STM32F7_I2C_DNF_MAX			16
> @@ -301,6 +303,8 @@ struct stm32f7_i2c_msg {
>   * @fmp_creg: register address for clearing Fast Mode Plus bits
>   * @fmp_mask: mask for Fast Mode Plus bits in set register
>   * @wakeup_src: boolean to know if the device is a wakeup source
> + * @smbus_mode: states that the controller is configured in SMBus mode
> + * @host_notify_client: SMBus host-notify client
>   */
>  struct stm32f7_i2c_dev {
>  	struct i2c_adapter adap;
> @@ -327,6 +331,8 @@ struct stm32f7_i2c_dev {
>  	u32 fmp_creg;
>  	u32 fmp_mask;
>  	bool wakeup_src;
> +	bool smbus_mode;
> +	struct i2c_client *host_notify_client;
>  };
>  
>  /*
> @@ -1321,10 +1327,18 @@ static int stm32f7_i2c_get_free_slave_id(struct stm32f7_i2c_dev *i2c_dev,
>  	int i;
>  
>  	/*
> -	 * slave[0] supports 7-bit and 10-bit slave address
> -	 * slave[1] supports 7-bit slave address only
> +	 * slave[0] support only SMBus Host address (0x8)
> +	 * slave[1] supports 7-bit and 10-bit slave address
> +	 * slave[2] supports 7-bit slave address only
>  	 */
> -	for (i = STM32F7_I2C_MAX_SLAVE - 1; i >= 0; i--) {
> +	if (i2c_dev->smbus_mode && (slave->addr == 0x08)) {
> +		if (i2c_dev->slave[0])
> +			goto fail;
> +		*id = 0;
> +		return 0;
> +	}
> +
> +	for (i = STM32F7_I2C_MAX_SLAVE - 1; i > 0; i--) {
>  		if (i == 1 && (slave->flags & I2C_CLIENT_TEN))
>  			continue;
>  		if (!i2c_dev->slave[i]) {
> @@ -1333,6 +1347,7 @@ static int stm32f7_i2c_get_free_slave_id(struct stm32f7_i2c_dev *i2c_dev,
>  		}
>  	}
>  
> +fail:
>  	dev_err(dev, "Slave 0x%x could not be registered\n", slave->addr);
>  
>  	return -EINVAL;
> @@ -1776,7 +1791,13 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
>  	if (!stm32f7_i2c_is_slave_registered(i2c_dev))
>  		stm32f7_i2c_enable_wakeup(i2c_dev, true);
>  
> -	if (id == 0) {
> +	switch (id) {
> +	case 0:
> +		/* Slave SMBus Host */
> +		i2c_dev->slave[id] = slave;
> +		break;
> +
> +	case 1:
>  		/* Configure Own Address 1 */
>  		oar1 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR1);
>  		oar1 &= ~STM32F7_I2C_OAR1_MASK;
> @@ -1789,7 +1810,9 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
>  		oar1 |= STM32F7_I2C_OAR1_OA1EN;
>  		i2c_dev->slave[id] = slave;
>  		writel_relaxed(oar1, i2c_dev->base + STM32F7_I2C_OAR1);
> -	} else if (id == 1) {
> +		break;
> +
> +	case 2:
>  		/* Configure Own Address 2 */
>  		oar2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR2);
>  		oar2 &= ~STM32F7_I2C_OAR2_MASK;
> @@ -1802,7 +1825,10 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
>  		oar2 |= STM32F7_I2C_OAR2_OA2EN;
>  		i2c_dev->slave[id] = slave;
>  		writel_relaxed(oar2, i2c_dev->base + STM32F7_I2C_OAR2);
> -	} else {
> +		break;
> +
> +	default:
> +		dev_err(dev, "I2C slave id not supported\n");
>  		ret = -ENODEV;
>  		goto pm_free;
>  	}
> @@ -1843,10 +1869,10 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (id == 0) {
> +	if (id == 1) {
>  		mask = STM32F7_I2C_OAR1_OA1EN;
>  		stm32f7_i2c_clr_bits(base + STM32F7_I2C_OAR1, mask);
> -	} else {
> +	} else if (id == 2) {
>  		mask = STM32F7_I2C_OAR2_OA2EN;
>  		stm32f7_i2c_clr_bits(base + STM32F7_I2C_OAR2, mask);
>  	}
> @@ -1911,14 +1937,51 @@ static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
>  					  &i2c_dev->fmp_mask);
>  }
>  
> +static int stm32f7_i2c_enable_smbus_host(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	struct i2c_adapter *adap = &i2c_dev->adap;
> +	void __iomem *base = i2c_dev->base;
> +	struct i2c_client *client;
> +
> +	client = i2c_new_slave_host_notify_device(adap);
> +	if (IS_ERR(client))
> +		return PTR_ERR(client);
> +
> +	i2c_dev->host_notify_client = client;
> +
> +	/* Enable SMBus Host address */
> +	stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, STM32F7_I2C_CR1_SMBHEN);
> +
> +	return 0;
> +}
> +
> +static void stm32f7_i2c_disable_smbus_host(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	void __iomem *base = i2c_dev->base;
> +
> +	if (i2c_dev->host_notify_client) {
> +		/* Disable SMBus Host address */
> +		stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1,
> +				     STM32F7_I2C_CR1_SMBHEN);
> +		i2c_free_slave_host_notify_device(i2c_dev->host_notify_client);
> +	}
> +}
> +
>  static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
>  {
> -	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SLAVE |
> -		I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> -		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
> -		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
> -		I2C_FUNC_SMBUS_PROC_CALL | I2C_FUNC_SMBUS_PEC |
> -		I2C_FUNC_SMBUS_I2C_BLOCK;
> +	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> +
> +	u32 func = I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SLAVE |
> +		   I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> +		   I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
> +		   I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
> +		   I2C_FUNC_SMBUS_PROC_CALL | I2C_FUNC_SMBUS_PEC |
> +		   I2C_FUNC_SMBUS_I2C_BLOCK;
> +
> +	if (i2c_dev->smbus_mode)
> +		func |= I2C_FUNC_SMBUS_HOST_NOTIFY;
> +
> +	return func;
>  }
>  
>  static const struct i2c_algorithm stm32f7_i2c_algo = {
> @@ -2084,10 +2147,22 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  
>  	stm32f7_i2c_hw_config(i2c_dev);
>  
> +	i2c_dev->smbus_mode = of_property_read_bool(pdev->dev.of_node, "smbus");
> +
>  	ret = i2c_add_adapter(adap);
>  	if (ret)
>  		goto pm_disable;
>  
> +	if (i2c_dev->smbus_mode) {
> +		ret = stm32f7_i2c_enable_smbus_host(i2c_dev);
> +		if (ret) {
> +			dev_err(i2c_dev->dev,
> +				"failed to enable SMBus Host-Notify protocol (%d)\n",
> +				ret);
> +			goto i2c_adapter_remove;
> +		}
> +	}
> +
>  	dev_info(i2c_dev->dev, "STM32F7 I2C-%d bus adapter\n", adap->nr);
>  
>  	pm_runtime_mark_last_busy(i2c_dev->dev);
> @@ -2095,6 +2170,9 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +i2c_adapter_remove:
> +	i2c_del_adapter(adap);
> +
>  pm_disable:
>  	pm_runtime_put_noidle(i2c_dev->dev);
>  	pm_runtime_disable(i2c_dev->dev);
> @@ -2126,6 +2204,8 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
>  {
>  	struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
>  
> +	stm32f7_i2c_disable_smbus_host(i2c_dev);
> +
>  	i2c_del_adapter(&i2c_dev->adap);
>  	pm_runtime_get_sync(i2c_dev->dev);
>  
>