学习分享全志平台TWI子系统源码分析（3) 驱动层源码讲解

/* i2c-core.c - a device driver for the iic-bus interface */ /* ------------------------------------------------------------------------- */ /* Copyright (C) 1995-99 Simon G. Vogl 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. */ /* ------------------------------------------------------------------------- */ /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>. All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl> SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and Jean Delvare <jdelvare@suse.de> Mux support by Rodolfo Giometti <giometti@enneenne.com> and Michael Lawnick <michael.lawnick.ext@nsn.com> OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de> (based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and (c) 2013 Wolfram Sang <wsa@the-dreams.de> I2C ACPI code Copyright (C) 2014 Intel Corp Author: Lan Tianyu <tianyu.lan@intel.com> I2C slave support (c) 2014 by Wolfram Sang <wsa@sang-engineering.com> */ #define pr_fmt(fmt) "i2c-core: " fmt #include <dt-bindings/i2c/i2c.h> #include <asm/uaccess.h> #include <linux/acpi.h> #include <linux/clk/clk-conf.h> #include <linux/completion.h> #include <linux/delay.h> #include <linux/err.h> #include <linux/errno.h> #include <linux/gpio.h> #include <linux/hardirq.h> #include <linux/i2c.h> #include <linux/idr.h> #include <linux/init.h> #include <linux/irqflags.h> #include <linux/jump_label.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/of_device.h> #include <linux/of.h> #include <linux/of_irq.h> #include <linux/pm_domain.h> #include <linux/pm_runtime.h> #include <linux/pm_wakeirq.h> #include <linux/property.h> #include <linux/rwsem.h> #include <linux/slab.h> #include "i2c-core.h" #define CREATE_TRACE_POINTS #include <trace/events/i2c.h> #define I2C_ADDR_OFFSET_TEN_BIT 0xa000 #define I2C_ADDR_OFFSET_SLAVE 0x1000 /* core_lock protects i2c_adapter_idr, and guarantees that device detection, deletion of detected devices, and attach_adapter calls are serialized */ static DEFINE_MUTEX(core_lock); static DEFINE_IDR(i2c_adapter_idr); static struct device_type i2c_client_type; static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver); static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE; static bool is_registered; void i2c_transfer_trace_reg(void) { static_key_slow_inc(&i2c_trace_msg); } void i2c_transfer_trace_unreg(void) { static_key_slow_dec(&i2c_trace_msg); } #if defined(CONFIG_ACPI) struct i2c_acpi_handler_data { struct acpi_connection_info info; struct i2c_adapter *adapter; }; struct gsb_buffer { u8 status; u8 len; union { u16 wdata; u8 bdata; u8 data[0]; }; } __packed; struct i2c_acpi_lookup { struct i2c_board_info *info; acpi_handle adapter_handle; acpi_handle device_handle; acpi_handle search_handle; u32 speed; u32 min_speed; }; static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data) { struct i2c_acpi_lookup *lookup = data; struct i2c_board_info *info = lookup->info; struct acpi_resource_i2c_serialbus *sb; acpi_status status; if (info->addr || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) return 1; sb = &ares->data.i2c_serial_bus; if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C) return 1; status = acpi_get_handle(lookup->device_handle, sb->resource_source.string_ptr, &lookup->adapter_handle); if (!ACPI_SUCCESS(status)) return 1; info->addr = sb->slave_address; lookup->speed = sb->connection_speed; if (sb->access_mode == ACPI_I2C_10BIT_MODE) info->flags |= I2C_CLIENT_TEN; return 1; } static int i2c_acpi_do_lookup(struct acpi_device *adev, struct i2c_acpi_lookup *lookup) { struct i2c_board_info *info = lookup->info; struct list_head resource_list; int ret; if (acpi_bus_get_status(adev) || !adev->status.present || acpi_device_enumerated(adev)) return -EINVAL; memset(info, 0, sizeof(*info)); lookup->device_handle = acpi_device_handle(adev); /* Look up for I2cSerialBus resource */ INIT_LIST_HEAD(&resource_list); ret = acpi_dev_get_resources(adev, &resource_list, i2c_acpi_fill_info, lookup); acpi_dev_free_resource_list(&resource_list); if (ret < 0 || !info->addr) return -EINVAL; return 0; } static int i2c_acpi_get_info(struct acpi_device *adev, struct i2c_board_info *info, struct i2c_adapter *adapter, acpi_handle *adapter_handle) { struct list_head resource_list; struct resource_entry *entry; struct i2c_acpi_lookup lookup; int ret; memset(&lookup, 0, sizeof(lookup)); lookup.info = info; ret = i2c_acpi_do_lookup(adev, &lookup); if (ret) return ret; if (adapter) { /* The adapter must match the one in I2cSerialBus() connector */ if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle) return -ENODEV; } else { struct acpi_device *adapter_adev; /* The adapter must be present */ if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev)) return -ENODEV; if (acpi_bus_get_status(adapter_adev) || !adapter_adev->status.present) return -ENODEV; } info->fwnode = acpi_fwnode_handle(adev); if (adapter_handle) *adapter_handle = lookup.adapter_handle; /* Then fill IRQ number if any */ INIT_LIST_HEAD(&resource_list); ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL); if (ret < 0) return -EINVAL; resource_list_for_each_entry(entry, &resource_list) { if (resource_type(entry->res) == IORESOURCE_IRQ) { info->irq = entry->res->start; break; } } acpi_dev_free_resource_list(&resource_list); strlcpy(info->type, dev_name(&adev->dev), sizeof(info->type)); return 0; } static void i2c_acpi_register_device(struct i2c_adapter *adapter, struct acpi_device *adev, struct i2c_board_info *info) { adev->power.flags.ignore_parent = true; acpi_device_set_enumerated(adev); if (!i2c_new_device(adapter, info)) { adev->power.flags.ignore_parent = false; dev_err(&adapter->dev, "failed to add I2C device %s from ACPI\n", dev_name(&adev->dev)); } } static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, void *data, void **return_value) { struct i2c_adapter *adapter = data; struct acpi_device *adev; struct i2c_board_info info; if (acpi_bus_get_device(handle, &adev)) return AE_OK; if (i2c_acpi_get_info(adev, &info, adapter, NULL)) return AE_OK; i2c_acpi_register_device(adapter, adev, &info); return AE_OK; } #define I2C_ACPI_MAX_SCAN_DEPTH 32 /** * i2c_acpi_register_devices - enumerate I2C slave devices behind adapter * @adap: pointer to adapter * * Enumerate all I2C slave devices behind this adapter by walking the ACPI * namespace. When a device is found it will be added to the Linux device * model and bound to the corresponding ACPI handle. */ static void i2c_acpi_register_devices(struct i2c_adapter *adap) { acpi_status status; if (!has_acpi_companion(&adap->dev)) return; status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, I2C_ACPI_MAX_SCAN_DEPTH, i2c_acpi_add_device, NULL, adap, NULL); if (ACPI_FAILURE(status)) dev_warn(&adap->dev, "failed to enumerate I2C slaves\n"); } static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level, void *data, void **return_value) { struct i2c_acpi_lookup *lookup = data; struct acpi_device *adev; if (acpi_bus_get_device(handle, &adev)) return AE_OK; if (i2c_acpi_do_lookup(adev, lookup))