|
|
@@ -0,0 +1,263 @@
|
|
|
+/*
|
|
|
+ * i2c-smbus.c - SMBus extensions to the I2C protocol
|
|
|
+ *
|
|
|
+ * Copyright (C) 2008 David Brownell
|
|
|
+ * Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
|
|
|
+ *
|
|
|
+ * This program is free software; you can redistribute it and/or modify
|
|
|
+ * it under the terms of the GNU General Public License as published by
|
|
|
+ * the Free Software Foundation; either version 2 of the License, or
|
|
|
+ * (at your option) any later version.
|
|
|
+ *
|
|
|
+ * This program is distributed in the hope that it will be useful,
|
|
|
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
|
+ * GNU General Public License for more details.
|
|
|
+ *
|
|
|
+ * You should have received a copy of the GNU General Public License
|
|
|
+ * along with this program; if not, write to the Free Software
|
|
|
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
|
+ */
|
|
|
+
|
|
|
+#include <linux/kernel.h>
|
|
|
+#include <linux/module.h>
|
|
|
+#include <linux/device.h>
|
|
|
+#include <linux/semaphore.h>
|
|
|
+#include <linux/interrupt.h>
|
|
|
+#include <linux/workqueue.h>
|
|
|
+#include <linux/i2c.h>
|
|
|
+#include <linux/i2c-smbus.h>
|
|
|
+
|
|
|
+struct i2c_smbus_alert {
|
|
|
+ unsigned int alert_edge_triggered:1;
|
|
|
+ int irq;
|
|
|
+ struct work_struct alert;
|
|
|
+ struct i2c_client *ara; /* Alert response address */
|
|
|
+};
|
|
|
+
|
|
|
+struct alert_data {
|
|
|
+ unsigned short addr;
|
|
|
+ u8 flag:1;
|
|
|
+};
|
|
|
+
|
|
|
+/* If this is the alerting device, notify its driver */
|
|
|
+static int smbus_do_alert(struct device *dev, void *addrp)
|
|
|
+{
|
|
|
+ struct i2c_client *client = i2c_verify_client(dev);
|
|
|
+ struct alert_data *data = addrp;
|
|
|
+
|
|
|
+ if (!client || client->addr != data->addr)
|
|
|
+ return 0;
|
|
|
+ if (client->flags & I2C_CLIENT_TEN)
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Drivers should either disable alerts, or provide at least
|
|
|
+ * a minimal handler. Lock so client->driver won't change.
|
|
|
+ */
|
|
|
+ down(&dev->sem);
|
|
|
+ if (client->driver) {
|
|
|
+ if (client->driver->alert)
|
|
|
+ client->driver->alert(client, data->flag);
|
|
|
+ else
|
|
|
+ dev_warn(&client->dev, "no driver alert()!\n");
|
|
|
+ } else
|
|
|
+ dev_dbg(&client->dev, "alert with no driver\n");
|
|
|
+ up(&dev->sem);
|
|
|
+
|
|
|
+ /* Stop iterating after we find the device */
|
|
|
+ return -EBUSY;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * The alert IRQ handler needs to hand work off to a task which can issue
|
|
|
+ * SMBus calls, because those sleeping calls can't be made in IRQ context.
|
|
|
+ */
|
|
|
+static void smbus_alert(struct work_struct *work)
|
|
|
+{
|
|
|
+ struct i2c_smbus_alert *alert;
|
|
|
+ struct i2c_client *ara;
|
|
|
+ unsigned short prev_addr = 0; /* Not a valid address */
|
|
|
+
|
|
|
+ alert = container_of(work, struct i2c_smbus_alert, alert);
|
|
|
+ ara = alert->ara;
|
|
|
+
|
|
|
+ for (;;) {
|
|
|
+ s32 status;
|
|
|
+ struct alert_data data;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Devices with pending alerts reply in address order, low
|
|
|
+ * to high, because of slave transmit arbitration. After
|
|
|
+ * responding, an SMBus device stops asserting SMBALERT#.
|
|
|
+ *
|
|
|
+ * Note that SMBus 2.0 reserves 10-bit addresess for future
|
|
|
+ * use. We neither handle them, nor try to use PEC here.
|
|
|
+ */
|
|
|
+ status = i2c_smbus_read_byte(ara);
|
|
|
+ if (status < 0)
|
|
|
+ break;
|
|
|
+
|
|
|
+ data.flag = status & 1;
|
|
|
+ data.addr = status >> 1;
|
|
|
+
|
|
|
+ if (data.addr == prev_addr) {
|
|
|
+ dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
|
|
|
+ "0x%02x, skipping\n", data.addr);
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
|
|
|
+ data.addr, data.flag);
|
|
|
+
|
|
|
+ /* Notify driver for the device which issued the alert */
|
|
|
+ device_for_each_child(&ara->adapter->dev, &data,
|
|
|
+ smbus_do_alert);
|
|
|
+ prev_addr = data.addr;
|
|
|
+ }
|
|
|
+
|
|
|
+ /* We handled all alerts; re-enable level-triggered IRQs */
|
|
|
+ if (!alert->alert_edge_triggered)
|
|
|
+ enable_irq(alert->irq);
|
|
|
+}
|
|
|
+
|
|
|
+static irqreturn_t smbalert_irq(int irq, void *d)
|
|
|
+{
|
|
|
+ struct i2c_smbus_alert *alert = d;
|
|
|
+
|
|
|
+ /* Disable level-triggered IRQs until we handle them */
|
|
|
+ if (!alert->alert_edge_triggered)
|
|
|
+ disable_irq_nosync(irq);
|
|
|
+
|
|
|
+ schedule_work(&alert->alert);
|
|
|
+ return IRQ_HANDLED;
|
|
|
+}
|
|
|
+
|
|
|
+/* Setup SMBALERT# infrastructure */
|
|
|
+static int smbalert_probe(struct i2c_client *ara,
|
|
|
+ const struct i2c_device_id *id)
|
|
|
+{
|
|
|
+ struct i2c_smbus_alert_setup *setup = ara->dev.platform_data;
|
|
|
+ struct i2c_smbus_alert *alert;
|
|
|
+ struct i2c_adapter *adapter = ara->adapter;
|
|
|
+ int res;
|
|
|
+
|
|
|
+ alert = kzalloc(sizeof(struct i2c_smbus_alert), GFP_KERNEL);
|
|
|
+ if (!alert)
|
|
|
+ return -ENOMEM;
|
|
|
+
|
|
|
+ alert->alert_edge_triggered = setup->alert_edge_triggered;
|
|
|
+ alert->irq = setup->irq;
|
|
|
+ INIT_WORK(&alert->alert, smbus_alert);
|
|
|
+ alert->ara = ara;
|
|
|
+
|
|
|
+ if (setup->irq > 0) {
|
|
|
+ res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
|
|
|
+ 0, "smbus_alert", alert);
|
|
|
+ if (res) {
|
|
|
+ kfree(alert);
|
|
|
+ return res;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ i2c_set_clientdata(ara, alert);
|
|
|
+ dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
|
|
|
+ setup->alert_edge_triggered ? "edge" : "level");
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/* IRQ resource is managed so it is freed automatically */
|
|
|
+static int smbalert_remove(struct i2c_client *ara)
|
|
|
+{
|
|
|
+ struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
|
|
|
+
|
|
|
+ cancel_work_sync(&alert->alert);
|
|
|
+
|
|
|
+ i2c_set_clientdata(ara, NULL);
|
|
|
+ kfree(alert);
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static const struct i2c_device_id smbalert_ids[] = {
|
|
|
+ { "smbus_alert", 0 },
|
|
|
+ { /* LIST END */ }
|
|
|
+};
|
|
|
+MODULE_DEVICE_TABLE(i2c, smbalert_ids);
|
|
|
+
|
|
|
+static struct i2c_driver smbalert_driver = {
|
|
|
+ .driver = {
|
|
|
+ .name = "smbus_alert",
|
|
|
+ },
|
|
|
+ .probe = smbalert_probe,
|
|
|
+ .remove = smbalert_remove,
|
|
|
+ .id_table = smbalert_ids,
|
|
|
+};
|
|
|
+
|
|
|
+/**
|
|
|
+ * i2c_setup_smbus_alert - Setup SMBus alert support
|
|
|
+ * @adapter: the target adapter
|
|
|
+ * @setup: setup data for the SMBus alert handler
|
|
|
+ * Context: can sleep
|
|
|
+ *
|
|
|
+ * Setup handling of the SMBus alert protocol on a given I2C bus segment.
|
|
|
+ *
|
|
|
+ * Handling can be done either through our IRQ handler, or by the
|
|
|
+ * adapter (from its handler, periodic polling, or whatever).
|
|
|
+ *
|
|
|
+ * NOTE that if we manage the IRQ, we *MUST* know if it's level or
|
|
|
+ * edge triggered in order to hand it to the workqueue correctly.
|
|
|
+ * If triggering the alert seems to wedge the system, you probably
|
|
|
+ * should have said it's level triggered.
|
|
|
+ *
|
|
|
+ * This returns the ara client, which should be saved for later use with
|
|
|
+ * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
|
|
|
+ * to indicate an error.
|
|
|
+ */
|
|
|
+struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
|
|
|
+ struct i2c_smbus_alert_setup *setup)
|
|
|
+{
|
|
|
+ struct i2c_board_info ara_board_info = {
|
|
|
+ I2C_BOARD_INFO("smbus_alert", 0x0c),
|
|
|
+ .platform_data = setup,
|
|
|
+ };
|
|
|
+
|
|
|
+ return i2c_new_device(adapter, &ara_board_info);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
|
|
|
+
|
|
|
+/**
|
|
|
+ * i2c_handle_smbus_alert - Handle an SMBus alert
|
|
|
+ * @ara: the ARA client on the relevant adapter
|
|
|
+ * Context: can't sleep
|
|
|
+ *
|
|
|
+ * Helper function to be called from an I2C bus driver's interrupt
|
|
|
+ * handler. It will schedule the alert work, in turn calling the
|
|
|
+ * corresponding I2C device driver's alert function.
|
|
|
+ *
|
|
|
+ * It is assumed that ara is a valid i2c client previously returned by
|
|
|
+ * i2c_setup_smbus_alert().
|
|
|
+ */
|
|
|
+int i2c_handle_smbus_alert(struct i2c_client *ara)
|
|
|
+{
|
|
|
+ struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
|
|
|
+
|
|
|
+ return schedule_work(&alert->alert);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
|
|
|
+
|
|
|
+static int __init i2c_smbus_init(void)
|
|
|
+{
|
|
|
+ return i2c_add_driver(&smbalert_driver);
|
|
|
+}
|
|
|
+
|
|
|
+static void __exit i2c_smbus_exit(void)
|
|
|
+{
|
|
|
+ i2c_del_driver(&smbalert_driver);
|
|
|
+}
|
|
|
+
|
|
|
+module_init(i2c_smbus_init);
|
|
|
+module_exit(i2c_smbus_exit);
|
|
|
+
|
|
|
+MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
|
|
|
+MODULE_DESCRIPTION("SMBus protocol extensions support");
|
|
|
+MODULE_LICENSE("GPL");
|
Jean Delvare