1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Driver for the Intel SCU IPC mechanism 4 * 5 * (C) Copyright 2008-2010 Intel Corporation 6 * Author: Sreedhara DS (sreedhara.ds@intel.com) 7 * 8 * This driver provides IOCTL interfaces to call Intel SCU IPC driver API. 9 */ 10 11 #include <linux/errno.h> 12 #include <linux/fcntl.h> 13 #include <linux/fs.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/sched.h> 17 #include <linux/slab.h> 18 #include <linux/types.h> 19 #include <linux/uaccess.h> 20 21 #include <asm/intel_scu_ipc.h> 22 23 static int major; 24 25 static struct intel_scu_ipc_dev *scu; 26 static DEFINE_MUTEX(scu_lock); 27 28 /* IOCTL commands */ 29 #define INTE_SCU_IPC_REGISTER_READ 0 30 #define INTE_SCU_IPC_REGISTER_WRITE 1 31 #define INTE_SCU_IPC_REGISTER_UPDATE 2 32 33 struct scu_ipc_data { 34 u32 count; /* No. of registers */ 35 u16 addr[5]; /* Register addresses */ 36 u8 data[5]; /* Register data */ 37 u8 mask; /* Valid for read-modify-write */ 38 }; 39 40 /** 41 * scu_reg_access - implement register access ioctls 42 * @cmd: command we are doing (read/write/update) 43 * @data: kernel copy of ioctl data 44 * 45 * Allow the user to perform register accesses on the SCU via the 46 * kernel interface 47 */ 48 49 static int scu_reg_access(u32 cmd, struct scu_ipc_data *data) 50 { 51 unsigned int count = data->count; 52 53 if (count == 0 || count == 3 || count > 4) 54 return -EINVAL; 55 56 switch (cmd) { 57 case INTE_SCU_IPC_REGISTER_READ: 58 return intel_scu_ipc_dev_readv(scu, data->addr, data->data, count); 59 case INTE_SCU_IPC_REGISTER_WRITE: 60 return intel_scu_ipc_dev_writev(scu, data->addr, data->data, count); 61 case INTE_SCU_IPC_REGISTER_UPDATE: 62 return intel_scu_ipc_dev_update(scu, data->addr[0], data->data[0], 63 data->mask); 64 default: 65 return -ENOTTY; 66 } 67 } 68 69 /** 70 * scu_ipc_ioctl - control ioctls for the SCU 71 * @fp: file handle of the SCU device 72 * @cmd: ioctl coce 73 * @arg: pointer to user passed structure 74 * 75 * Support the I/O and firmware flashing interfaces of the SCU 76 */ 77 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd, 78 unsigned long arg) 79 { 80 int ret; 81 struct scu_ipc_data data; 82 void __user *argp = (void __user *)arg; 83 84 if (!capable(CAP_SYS_RAWIO)) 85 return -EPERM; 86 87 if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data))) 88 return -EFAULT; 89 ret = scu_reg_access(cmd, &data); 90 if (ret < 0) 91 return ret; 92 if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data))) 93 return -EFAULT; 94 return 0; 95 } 96 97 static int scu_ipc_open(struct inode *inode, struct file *file) 98 { 99 int ret = 0; 100 101 /* Only single open at the time */ 102 mutex_lock(&scu_lock); 103 if (scu) { 104 ret = -EBUSY; 105 goto unlock; 106 } 107 108 scu = intel_scu_ipc_dev_get(); 109 if (!scu) 110 ret = -ENODEV; 111 112 unlock: 113 mutex_unlock(&scu_lock); 114 return ret; 115 } 116 117 static int scu_ipc_release(struct inode *inode, struct file *file) 118 { 119 mutex_lock(&scu_lock); 120 intel_scu_ipc_dev_put(scu); 121 scu = NULL; 122 mutex_unlock(&scu_lock); 123 124 return 0; 125 } 126 127 static const struct file_operations scu_ipc_fops = { 128 .unlocked_ioctl = scu_ipc_ioctl, 129 .open = scu_ipc_open, 130 .release = scu_ipc_release, 131 }; 132 133 static int __init ipc_module_init(void) 134 { 135 major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops); 136 if (major < 0) 137 return major; 138 139 return 0; 140 } 141 142 static void __exit ipc_module_exit(void) 143 { 144 unregister_chrdev(major, "intel_mid_scu"); 145 } 146 147 module_init(ipc_module_init); 148 module_exit(ipc_module_exit); 149 150 MODULE_LICENSE("GPL v2"); 151 MODULE_DESCRIPTION("Utility driver for intel scu ipc"); 152 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>"); 153