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-rw-r--r--drivers/i2c/i2c-smbus.c415
1 files changed, 415 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
new file mode 100644
index 0000000000..138c3f5e00
--- /dev/null
+++ b/drivers/i2c/i2c-smbus.c
@@ -0,0 +1,415 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i2c-smbus.c - SMBus extensions to the I2C protocol
+ *
+ * Copyright (C) 2008 David Brownell
+ * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de>
+ */
+
+#include <linux/device.h>
+#include <linux/dmi.h>
+#include <linux/i2c.h>
+#include <linux/i2c-smbus.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+struct i2c_smbus_alert {
+ struct work_struct alert;
+ struct i2c_client *ara; /* Alert response address */
+};
+
+struct alert_data {
+ unsigned short addr;
+ enum i2c_alert_protocol type;
+ unsigned int data;
+};
+
+/* 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;
+ struct i2c_driver *driver;
+
+ 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 the driver won't change.
+ */
+ device_lock(dev);
+ if (client->dev.driver) {
+ driver = to_i2c_driver(client->dev.driver);
+ if (driver->alert)
+ driver->alert(client, data->type, data->data);
+ else
+ dev_warn(&client->dev, "no driver alert()!\n");
+ } else
+ dev_dbg(&client->dev, "alert with no driver\n");
+ device_unlock(dev);
+
+ /* 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 irqreturn_t smbus_alert(int irq, void *d)
+{
+ struct i2c_smbus_alert *alert = d;
+ struct i2c_client *ara;
+
+ 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 addresses for future
+ * use. We neither handle them, nor try to use PEC here.
+ */
+ status = i2c_smbus_read_byte(ara);
+ if (status < 0)
+ break;
+
+ data.data = status & 1;
+ data.addr = status >> 1;
+ data.type = I2C_PROTOCOL_SMBUS_ALERT;
+
+ dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
+ data.addr, data.data);
+
+ /* Notify driver for the device which issued the alert */
+ device_for_each_child(&ara->adapter->dev, &data,
+ smbus_do_alert);
+ }
+
+ return IRQ_HANDLED;
+}
+
+static void smbalert_work(struct work_struct *work)
+{
+ struct i2c_smbus_alert *alert;
+
+ alert = container_of(work, struct i2c_smbus_alert, alert);
+
+ smbus_alert(0, alert);
+
+}
+
+/* Setup SMBALERT# infrastructure */
+static int smbalert_probe(struct i2c_client *ara)
+{
+ struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
+ struct i2c_smbus_alert *alert;
+ struct i2c_adapter *adapter = ara->adapter;
+ int res, irq;
+
+ alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
+ GFP_KERNEL);
+ if (!alert)
+ return -ENOMEM;
+
+ if (setup) {
+ irq = setup->irq;
+ } else {
+ irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
+ "smbus_alert");
+ if (irq <= 0)
+ return irq;
+ }
+
+ INIT_WORK(&alert->alert, smbalert_work);
+ alert->ara = ara;
+
+ if (irq > 0) {
+ res = devm_request_threaded_irq(&ara->dev, irq,
+ NULL, smbus_alert,
+ IRQF_SHARED | IRQF_ONESHOT,
+ "smbus_alert", alert);
+ if (res)
+ return res;
+ }
+
+ i2c_set_clientdata(ara, alert);
+ dev_info(&adapter->dev, "supports SMBALERT#\n");
+
+ return 0;
+}
+
+/* IRQ and memory resources are managed so they are freed automatically */
+static void smbalert_remove(struct i2c_client *ara)
+{
+ struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
+
+ cancel_work_sync(&alert->alert);
+}
+
+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_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_new_smbus_alert_device().
+ */
+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);
+
+module_i2c_driver(smbalert_driver);
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+#define SMBUS_HOST_NOTIFY_LEN 3
+struct i2c_slave_host_notify_status {
+ u8 index;
+ u8 addr;
+};
+
+static int i2c_slave_host_notify_cb(struct i2c_client *client,
+ enum i2c_slave_event event, u8 *val)
+{
+ struct i2c_slave_host_notify_status *status = client->dev.platform_data;
+
+ switch (event) {
+ 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->index == 0)
+ status->addr = *val;
+ if (status->index < U8_MAX)
+ status->index++;
+ break;
+ case I2C_SLAVE_STOP:
+ if (status->index == SMBUS_HOST_NOTIFY_LEN)
+ i2c_handle_smbus_host_notify(client->adapter,
+ status->addr);
+ fallthrough;
+ case I2C_SLAVE_WRITE_REQUESTED:
+ status->index = 0;
+ break;
+ case I2C_SLAVE_READ_REQUESTED:
+ case I2C_SLAVE_READ_PROCESSED:
+ *val = 0xff;
+ break;
+ }
+
+ return 0;
+}
+
+/**
+ * i2c_new_slave_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_slave_host_notify_device(); or an ERRPTR to indicate an error.
+ */
+struct i2c_client *i2c_new_slave_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_slave_host_notify_status *status;
+ struct i2c_client *client;
+ int ret;
+
+ status = kzalloc(sizeof(struct i2c_slave_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_slave_host_notify_cb);
+ if (ret) {
+ i2c_unregister_device(client);
+ kfree(status);
+ return ERR_PTR(ret);
+ }
+
+ return client;
+}
+EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);
+
+/**
+ * i2c_free_slave_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_slave_host_notify_device
+ */
+void i2c_free_slave_host_notify_device(struct i2c_client *client)
+{
+ if (IS_ERR_OR_NULL(client))
+ return;
+
+ i2c_slave_unregister(client);
+ kfree(client->dev.platform_data);
+ i2c_unregister_device(client);
+}
+EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
+#endif
+
+/*
+ * SPD is not part of SMBus but we include it here for convenience as the
+ * target systems are the same.
+ * Restrictions to automatic SPD instantiation:
+ * - Only works if all filled slots have the same memory type
+ * - Only works for DDR2, DDR3 and DDR4 for now
+ * - Only works on systems with 1 to 4 memory slots
+ */
+#if IS_ENABLED(CONFIG_DMI)
+void i2c_register_spd(struct i2c_adapter *adap)
+{
+ int n, slot_count = 0, dimm_count = 0;
+ u16 handle;
+ u8 common_mem_type = 0x0, mem_type;
+ u64 mem_size;
+ const char *name;
+
+ while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
+ slot_count++;
+
+ /* Skip empty slots */
+ mem_size = dmi_memdev_size(handle);
+ if (!mem_size)
+ continue;
+
+ /* Skip undefined memory type */
+ mem_type = dmi_memdev_type(handle);
+ if (mem_type <= 0x02) /* Invalid, Other, Unknown */
+ continue;
+
+ if (!common_mem_type) {
+ /* First filled slot */
+ common_mem_type = mem_type;
+ } else {
+ /* Check that all filled slots have the same type */
+ if (mem_type != common_mem_type) {
+ dev_warn(&adap->dev,
+ "Different memory types mixed, not instantiating SPD\n");
+ return;
+ }
+ }
+ dimm_count++;
+ }
+
+ /* No useful DMI data, bail out */
+ if (!dimm_count)
+ return;
+
+ dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
+ dimm_count, slot_count);
+
+ if (slot_count > 4) {
+ dev_warn(&adap->dev,
+ "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n");
+ return;
+ }
+
+ /*
+ * Memory types could be found at section 7.18.2 (Memory Device — Type), table 78
+ * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
+ */
+ switch (common_mem_type) {
+ case 0x12: /* DDR */
+ case 0x13: /* DDR2 */
+ case 0x18: /* DDR3 */
+ case 0x1B: /* LPDDR */
+ case 0x1C: /* LPDDR2 */
+ case 0x1D: /* LPDDR3 */
+ name = "spd";
+ break;
+ case 0x1A: /* DDR4 */
+ case 0x1E: /* LPDDR4 */
+ name = "ee1004";
+ break;
+ default:
+ dev_info(&adap->dev,
+ "Memory type 0x%02x not supported yet, not instantiating SPD\n",
+ common_mem_type);
+ return;
+ }
+
+ /*
+ * We don't know in which slots the memory modules are. We could
+ * try to guess from the slot names, but that would be rather complex
+ * and unreliable, so better probe all possible addresses until we
+ * have found all memory modules.
+ */
+ for (n = 0; n < slot_count && dimm_count; n++) {
+ struct i2c_board_info info;
+ unsigned short addr_list[2];
+
+ memset(&info, 0, sizeof(struct i2c_board_info));
+ strscpy(info.type, name, I2C_NAME_SIZE);
+ addr_list[0] = 0x50 + n;
+ addr_list[1] = I2C_CLIENT_END;
+
+ if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {
+ dev_info(&adap->dev,
+ "Successfully instantiated SPD at 0x%hx\n",
+ addr_list[0]);
+ dimm_count--;
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(i2c_register_spd);
+#endif
+
+MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
+MODULE_DESCRIPTION("SMBus protocol extensions support");
+MODULE_LICENSE("GPL");