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From: Alain Volmat <alain.volmat@st.com>
To: <wsa@kernel.org>, <robh+dt@kernel.org>
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
	alexandre.torgue@st.com, linux-kernel@vger.kernel.org,
	pierre-yves.mordret@st.com, alain.volmat@st.com,
	linux-i2c@vger.kernel.org, mcoquelin.stm32@gmail.com,
	fabrice.gasnier@st.com, linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/4] i2c: smbus: add core function handling SMBus host-notify
Date: Thu, 25 Jun 2020 09:39:26 +0200
Message-ID: <1593070769-9106-2-git-send-email-alain.volmat@st.com> (raw)
In-Reply-To: <1593070769-9106-1-git-send-email-alain.volmat@st.com>

SMBus Host-Notify protocol, from the adapter point of view
consist of receiving a message from a client, including the
client address and some other data.

It can be simply handled by creating a new slave device
and registering a callback performing the parsing of the
message received from the client.

This commit introduces two new core functions
  * i2c_new_smbus_host_notify_device
  * i2c_free_smbus_host_notify_device
that take care of registration of the new slave device and
callback and will call i2c_handle_smbus_host_notify once a
Host-Notify event is received.

Signed-off-by: Alain Volmat <alain.volmat@st.com>
---
v2: remove useless dev_err message in case of hnotify handling error
    prevent handling hnotify in case of a incomplete write

 drivers/i2c/i2c-core-smbus.c | 110 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c-smbus.h    |   2 +
 2 files changed, 112 insertions(+)

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 56bb840142e3..3a37664fb5f6 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -708,3 +708,113 @@ int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter)
 }
 EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
 #endif
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+struct i2c_smbus_host_notify_status {
+	bool notify_start;
+	u8 addr;
+};
+
+static int i2c_smbus_host_notify_cb(struct i2c_client *client,
+				    enum i2c_slave_event event, u8 *val)
+{
+	struct i2c_smbus_host_notify_status *status = client->dev.platform_data;
+	int ret;
+
+	switch (event) {
+	case I2C_SLAVE_WRITE_REQUESTED:
+		status->notify_start = true;
+		break;
+	case I2C_SLAVE_WRITE_RECEIVED:
+		/* We only retrieve the first byte received (addr)
+		 * since there is currently no support to retrieve the data
+		 * parameter from the client.
+		 */
+		if (!status->notify_start)
+			break;
+		status->addr = *val;
+		status->notify_start = false;
+		break;
+	case I2C_SLAVE_STOP:
+		/* In case of incomplete write, don't handle host-notify */
+		if (status->notify_start) {
+			status->notify_start = false;
+			break;
+		}
+
+		ret = i2c_handle_smbus_host_notify(client->adapter,
+						   status->addr);
+		if (ret < 0)
+			return ret;
+		break;
+	default:
+		/* Only handle necessary events */
+		break;
+	}
+
+	return 0;
+}
+
+/**
+ * i2c_new_smbus_host_notify_device - get a client for SMBus host-notify support
+ * @adapter: the target adapter
+ * Context: can sleep
+ *
+ * Setup handling of the SMBus host-notify protocol on a given I2C bus segment.
+ *
+ * Handling is done by creating a device and its callback and handling data
+ * received via the SMBus host-notify address (0x8)
+ *
+ * This returns the client, which should be ultimately freed using
+ * i2c_free_smbus_host_notify_device(); or an ERRPTR to indicate an error.
+ */
+struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter)
+{
+	struct i2c_board_info host_notify_board_info = {
+		I2C_BOARD_INFO("smbus_host_notify", 0x08),
+		.flags  = I2C_CLIENT_SLAVE,
+	};
+	struct i2c_smbus_host_notify_status *status;
+	struct i2c_client *client;
+	int ret;
+
+	status = kzalloc(sizeof(struct i2c_smbus_host_notify_status),
+			 GFP_KERNEL);
+	if (!status)
+		return ERR_PTR(-ENOMEM);
+
+	host_notify_board_info.platform_data = status;
+
+	client = i2c_new_client_device(adapter, &host_notify_board_info);
+	if (IS_ERR(client)) {
+		kfree(status);
+		return client;
+	}
+
+	ret = i2c_slave_register(client, i2c_smbus_host_notify_cb);
+	if (ret) {
+		i2c_unregister_device(client);
+		kfree(status);
+		return ERR_PTR(ret);
+	}
+
+	return client;
+}
+EXPORT_SYMBOL_GPL(i2c_new_smbus_host_notify_device);
+
+/**
+ * i2c_free_smbus_host_notify_device - free the client for SMBus host-notify
+ * support
+ * @client: the client to free
+ * Context: can sleep
+ *
+ * Free the i2c_client allocated via i2c_new_smbus_host_notify_device
+ */
+void i2c_free_smbus_host_notify_device(struct i2c_client *client)
+{
+	i2c_slave_unregister(client);
+	kfree(client->dev.platform_data);
+	i2c_unregister_device(client);
+}
+EXPORT_SYMBOL_GPL(i2c_free_smbus_host_notify_device);
+#endif
diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
index 1e4e0de4ef8b..974038a684ed 100644
--- a/include/linux/i2c-smbus.h
+++ b/include/linux/i2c-smbus.h
@@ -38,6 +38,8 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
 	return 0;
 }
 #endif
+struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter);
+void i2c_free_smbus_host_notify_device(struct i2c_client *client);
 
 #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI)
 void i2c_register_spd(struct i2c_adapter *adap);
-- 
2.7.4


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Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25  7:39 [PATCH v2 0/4] stm32-f7: Addition of SMBus Alert / Host-notify features Alain Volmat
2020-06-25  7:39 ` Alain Volmat [this message]
2020-07-01 10:49   ` [PATCH v2 1/4] i2c: smbus: add core function handling SMBus host-notify Wolfram Sang
2020-07-02 11:23     ` Alain Volmat
2020-06-25  7:39 ` [PATCH v2 2/4] i2c: addition of client hnotify reg/unreg callbacks Alain Volmat
2020-06-25  7:39 ` [PATCH v2 3/4] dt-bindings: i2c-stm32: add SMBus Alert bindings Alain Volmat
2020-06-30 19:41   ` Wolfram Sang
2020-07-14  2:30     ` Rob Herring
2020-07-21  6:22       ` Wolfram Sang
2020-06-25  7:39 ` [PATCH v2 4/4] i2c: stm32f7: Add SMBus-specific protocols support Alain Volmat
2020-06-30 16:05 ` [PATCH v2 0/4] stm32-f7: Addition of SMBus Alert / Host-notify features Wolfram Sang
2020-07-01  9:21   ` Alain Volmat
2020-07-01  9:28     ` Wolfram Sang

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