diff options
Diffstat (limited to 'drivers/i2c/i2c-smbus.c')
| -rw-r--r-- | drivers/i2c/i2c-smbus.c | 415 |
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"); |