1 // SPDX-License-Identifier: GPL-2.0+ 2 // Expose the vboot context nvram to userspace 3 // 4 // Copyright (C) 2012 Google, Inc. 5 // Copyright (C) 2015 Collabora Ltd. 6 7 #include <linux/of.h> 8 #include <linux/platform_device.h> 9 #include <linux/module.h> 10 #include <linux/platform_data/cros_ec_commands.h> 11 #include <linux/platform_data/cros_ec_proto.h> 12 #include <linux/slab.h> 13 14 #define DRV_NAME "cros-ec-vbc" 15 16 static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj, 17 struct bin_attribute *att, char *buf, 18 loff_t pos, size_t count) 19 { 20 struct device *dev = container_of(kobj, struct device, kobj); 21 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 22 struct cros_ec_device *ecdev = ec->ec_dev; 23 struct ec_params_vbnvcontext *params; 24 struct cros_ec_command *msg; 25 int err; 26 const size_t para_sz = sizeof(params->op); 27 const size_t resp_sz = sizeof(struct ec_response_vbnvcontext); 28 const size_t payload = max(para_sz, resp_sz); 29 30 msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL); 31 if (!msg) 32 return -ENOMEM; 33 34 /* NB: we only kmalloc()ated enough space for the op field */ 35 params = (struct ec_params_vbnvcontext *)msg->data; 36 params->op = EC_VBNV_CONTEXT_OP_READ; 37 38 msg->version = EC_VER_VBNV_CONTEXT; 39 msg->command = EC_CMD_VBNV_CONTEXT; 40 msg->outsize = para_sz; 41 msg->insize = resp_sz; 42 43 err = cros_ec_cmd_xfer(ecdev, msg); 44 if (err < 0) { 45 dev_err(dev, "Error sending read request: %d\n", err); 46 kfree(msg); 47 return err; 48 } 49 50 memcpy(buf, msg->data, resp_sz); 51 52 kfree(msg); 53 return resp_sz; 54 } 55 56 static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj, 57 struct bin_attribute *attr, char *buf, 58 loff_t pos, size_t count) 59 { 60 struct device *dev = container_of(kobj, struct device, kobj); 61 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 62 struct cros_ec_device *ecdev = ec->ec_dev; 63 struct ec_params_vbnvcontext *params; 64 struct cros_ec_command *msg; 65 int err; 66 const size_t para_sz = sizeof(*params); 67 const size_t data_sz = sizeof(params->block); 68 69 /* Only write full values */ 70 if (count != data_sz) 71 return -EINVAL; 72 73 msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL); 74 if (!msg) 75 return -ENOMEM; 76 77 params = (struct ec_params_vbnvcontext *)msg->data; 78 params->op = EC_VBNV_CONTEXT_OP_WRITE; 79 memcpy(params->block, buf, data_sz); 80 81 msg->version = EC_VER_VBNV_CONTEXT; 82 msg->command = EC_CMD_VBNV_CONTEXT; 83 msg->outsize = para_sz; 84 msg->insize = 0; 85 86 err = cros_ec_cmd_xfer(ecdev, msg); 87 if (err < 0) { 88 dev_err(dev, "Error sending write request: %d\n", err); 89 kfree(msg); 90 return err; 91 } 92 93 kfree(msg); 94 return data_sz; 95 } 96 97 static BIN_ATTR_RW(vboot_context, 16); 98 99 static struct bin_attribute *cros_ec_vbc_bin_attrs[] = { 100 &bin_attr_vboot_context, 101 NULL 102 }; 103 104 static struct attribute_group cros_ec_vbc_attr_group = { 105 .name = "vbc", 106 .bin_attrs = cros_ec_vbc_bin_attrs, 107 }; 108 109 static int cros_ec_vbc_probe(struct platform_device *pd) 110 { 111 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 112 struct device *dev = &pd->dev; 113 int ret; 114 115 ret = sysfs_create_group(&ec_dev->class_dev.kobj, 116 &cros_ec_vbc_attr_group); 117 if (ret < 0) 118 dev_err(dev, "failed to create %s attributes. err=%d\n", 119 cros_ec_vbc_attr_group.name, ret); 120 121 return ret; 122 } 123 124 static int cros_ec_vbc_remove(struct platform_device *pd) 125 { 126 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 127 128 sysfs_remove_group(&ec_dev->class_dev.kobj, 129 &cros_ec_vbc_attr_group); 130 131 return 0; 132 } 133 134 static struct platform_driver cros_ec_vbc_driver = { 135 .driver = { 136 .name = DRV_NAME, 137 }, 138 .probe = cros_ec_vbc_probe, 139 .remove = cros_ec_vbc_remove, 140 }; 141 142 module_platform_driver(cros_ec_vbc_driver); 143 144 MODULE_LICENSE("GPL"); 145 MODULE_DESCRIPTION("Expose the vboot context nvram to userspace"); 146 MODULE_ALIAS("platform:" DRV_NAME); 147