Re: [PATCH 4/4] i2c: stm32f7: Add SMBus-specific protocols support

Pierre Yves MORDRET
2020-05-11T08:27:57Z

Hi all,

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

Thanks

On 5/5/20 7:51 AM, Alain Volmat wrote:
> This patch adds the support for SMBus Host notify and SMBus Alert
> extensions protocols
>
> Signed-off-by: Alain Volmat <alain.volmat@st.com>
> ---
> drivers/i2c/busses/Kconfig | 1 +
> drivers/i2c/busses/i2c-stm32f7.c | 198 +++++++++++++++++++++++++++++--
> 2 files changed, 189 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 2f6e39b41e6c..b82c2f7d7d50 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1024,6 +1024,7 @@ 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 9c9e10ea9199..6d02ddbc1ab4 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -14,10 +14,12 @@
> * This driver is based on i2c-stm32f4.c
> *
> */
> +#include <linux/atomic.h>
> #include <linux/clk.h>
> #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 +52,8 @@
>
> /* 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)
> #define STM32F7_I2C_CR1_RXDMAEN BIT(15)
> @@ -121,6 +125,7 @@
> (((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)
> @@ -134,6 +139,7 @@
> #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)
> @@ -150,7 +156,7 @@
>
> #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
> @@ -274,6 +280,29 @@ struct stm32f7_i2c_msg {
> u8 smbus_buf[I2C_SMBUS_BLOCK_MAX + 3] __aligned(4);
> };
>
> +/**
> + * struct stm32f7_i2c_host - SMBus host specific data
> + * @client: I2C slave device that represents SMBus host
> + * @notify_start: indicate that this is the start of the notify transaction
> + * @addr: device address of SMBus device that initiate SMBus host protocol
> + */
> +struct stm32f7_i2c_host {
> + struct i2c_client *client;
> + bool notify_start;
> + u8 addr;
> +};
> +
> +/**
> + * 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
> @@ -301,6 +330,9 @@ 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
> + * @host_notify_cnt: atomic to know number of host_notify enabled clients
> + * @host_notify_client: SMBus host-notify client
> + * @alert: SMBus alert specific data
> */
> struct stm32f7_i2c_dev {
> struct i2c_adapter adap;
> @@ -327,6 +359,9 @@ struct stm32f7_i2c_dev {
> u32 fmp_creg;
> u32 fmp_mask;
> bool wakeup_src;
> + atomic_t host_notify_cnt;
> + struct i2c_client *host_notify_client;
> + struct stm32f7_i2c_alert *alert;
> };
>
> /*
> @@ -1321,10 +1356,20 @@ 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 (atomic_read(&i2c_dev->host_notify_cnt)) {
> + if (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 +1378,7 @@ 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;
> @@ -1586,6 +1632,13 @@ 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 */
> @@ -1776,7 +1829,13 @@ 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 +1848,9 @@ 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 +1863,10 @@ 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 +1907,10 @@ 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);
> }
> @@ -1911,6 +1975,103 @@ 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_smbus_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_smbus_host_notify_device(i2c_dev->host_notify_client);
> + }
> +}
> +
> +static int stm32f7_i2c_reg_client(struct i2c_client *client)
> +{
> + struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(client->adapter);
> + int ret;
> +
> + if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
> + /* Only enable on the first device registration */
> + if (atomic_inc_return(&i2c_dev->host_notify_cnt) == 1) {
> + ret = stm32f7_i2c_enable_smbus_host(i2c_dev);
> + if (ret) {
> + dev_err(i2c_dev->dev,
> + "failed to enable SMBus host notify (%d)\n",
> + ret);
> + return ret;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static void stm32f7_i2c_unreg_client(struct i2c_client *client)
> +{
> + struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(client->adapter);
> +
> + if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
> + if (atomic_dec_return(&i2c_dev->host_notify_cnt) == 0)
> + stm32f7_i2c_disable_smbus_host(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)
> {
> return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SLAVE |
> @@ -1918,7 +2079,7 @@ static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
> 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;
> + I2C_FUNC_SMBUS_I2C_BLOCK | I2C_FUNC_SMBUS_HOST_NOTIFY;
> }
>
> static const struct i2c_algorithm stm32f7_i2c_algo = {
> @@ -1927,6 +2088,8 @@ static const struct i2c_algorithm stm32f7_i2c_algo = {
> .functionality = stm32f7_i2c_func,
> .reg_slave = stm32f7_i2c_reg_slave,
> .unreg_slave = stm32f7_i2c_unreg_slave,
> + .reg_client = stm32f7_i2c_reg_client,
> + .unreg_client = stm32f7_i2c_unreg_client,
> };
>
> static int stm32f7_i2c_probe(struct platform_device *pdev)
> @@ -2088,6 +2251,16 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
> if (ret)
> goto pm_disable;
>
> + if (device_property_read_bool(&pdev->dev, "st,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_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 +2268,9 @@ 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 +2302,8 @@ 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);
> +
> i2c_del_adapter(&i2c_dev->adap);
> pm_runtime_get_sync(i2c_dev->dev);
>
>