1 /* 2 * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism 3 * 4 * (C) Copyright 2008-2010 Intel Corporation 5 * Author: Sreedhara DS (sreedhara.ds@intel.com) 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; version 2 10 * of the License. 11 * 12 * This driver provides ioctl interfaces to call intel scu ipc driver api 13 */ 14 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 #include <linux/errno.h> 18 #include <linux/types.h> 19 #include <linux/fs.h> 20 #include <linux/fcntl.h> 21 #include <linux/sched.h> 22 #include <linux/uaccess.h> 23 #include <linux/slab.h> 24 #include <linux/init.h> 25 #include <asm/intel_scu_ipc.h> 26 27 static int major; 28 29 /* ioctl commnds */ 30 #define INTE_SCU_IPC_REGISTER_READ 0 31 #define INTE_SCU_IPC_REGISTER_WRITE 1 32 #define INTE_SCU_IPC_REGISTER_UPDATE 2 33 34 struct scu_ipc_data { 35 u32 count; /* No. of registers */ 36 u16 addr[5]; /* Register addresses */ 37 u8 data[5]; /* Register data */ 38 u8 mask; /* Valid for read-modify-write */ 39 }; 40 41 /** 42 * scu_reg_access - implement register access ioctls 43 * @cmd: command we are doing (read/write/update) 44 * @data: kernel copy of ioctl data 45 * 46 * Allow the user to perform register accesses on the SCU via the 47 * kernel interface 48 */ 49 50 static int scu_reg_access(u32 cmd, struct scu_ipc_data *data) 51 { 52 int count = data->count; 53 54 if (count == 0 || count == 3 || count > 4) 55 return -EINVAL; 56 57 switch (cmd) { 58 case INTE_SCU_IPC_REGISTER_READ: 59 return intel_scu_ipc_readv(data->addr, data->data, count); 60 case INTE_SCU_IPC_REGISTER_WRITE: 61 return intel_scu_ipc_writev(data->addr, data->data, count); 62 case INTE_SCU_IPC_REGISTER_UPDATE: 63 return intel_scu_ipc_update_register(data->addr[0], 64 data->data[0], data->mask); 65 default: 66 return -ENOTTY; 67 } 68 } 69 70 /** 71 * scu_ipc_ioctl - control ioctls for the SCU 72 * @fp: file handle of the SCU device 73 * @cmd: ioctl coce 74 * @arg: pointer to user passed structure 75 * 76 * Support the I/O and firmware flashing interfaces of the SCU 77 */ 78 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd, 79 unsigned long arg) 80 { 81 int ret; 82 struct scu_ipc_data data; 83 void __user *argp = (void __user *)arg; 84 85 if (!capable(CAP_SYS_RAWIO)) 86 return -EPERM; 87 88 if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data))) 89 return -EFAULT; 90 ret = scu_reg_access(cmd, &data); 91 if (ret < 0) 92 return ret; 93 if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data))) 94 return -EFAULT; 95 return 0; 96 } 97 98 static const struct file_operations scu_ipc_fops = { 99 .unlocked_ioctl = scu_ipc_ioctl, 100 }; 101 102 static int __init ipc_module_init(void) 103 { 104 major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops); 105 if (major < 0) 106 return major; 107 108 return 0; 109 } 110 111 static void __exit ipc_module_exit(void) 112 { 113 unregister_chrdev(major, "intel_mid_scu"); 114 } 115 116 module_init(ipc_module_init); 117 module_exit(ipc_module_exit); 118 119 MODULE_LICENSE("GPL v2"); 120 MODULE_DESCRIPTION("Utility driver for intel scu ipc"); 121 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>"); 122