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/mod_devicetable.h> 10 #include <linux/module.h> 11 #include <linux/platform_data/cros_ec_commands.h> 12 #include <linux/platform_data/cros_ec_proto.h> 13 #include <linux/slab.h> 14 15 #define DRV_NAME "cros-ec-vbc" 16 17 static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj, 18 struct bin_attribute *att, char *buf, 19 loff_t pos, size_t count) 20 { 21 struct device *dev = kobj_to_dev(kobj); 22 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 23 struct cros_ec_device *ecdev = ec->ec_dev; 24 struct cros_ec_command *msg; 25 /* 26 * This should be a pointer to the same type as op field in 27 * struct ec_params_vbnvcontext. 28 */ 29 uint32_t *params_op; 30 int err; 31 const size_t para_sz = sizeof(*params_op); 32 const size_t resp_sz = sizeof(struct ec_response_vbnvcontext); 33 const size_t payload = max(para_sz, resp_sz); 34 35 msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL); 36 if (!msg) 37 return -ENOMEM; 38 39 /* NB: we only kmalloc()ated enough space for the op field */ 40 params_op = (uint32_t *)msg->data; 41 *params_op = EC_VBNV_CONTEXT_OP_READ; 42 43 msg->version = EC_VER_VBNV_CONTEXT; 44 msg->command = EC_CMD_VBNV_CONTEXT; 45 msg->outsize = para_sz; 46 msg->insize = resp_sz; 47 48 err = cros_ec_cmd_xfer_status(ecdev, msg); 49 if (err < 0) { 50 dev_err(dev, "Error sending read request: %d\n", err); 51 kfree(msg); 52 return err; 53 } 54 55 memcpy(buf, msg->data, resp_sz); 56 57 kfree(msg); 58 return resp_sz; 59 } 60 61 static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj, 62 struct bin_attribute *attr, char *buf, 63 loff_t pos, size_t count) 64 { 65 struct device *dev = kobj_to_dev(kobj); 66 struct cros_ec_dev *ec = to_cros_ec_dev(dev); 67 struct cros_ec_device *ecdev = ec->ec_dev; 68 struct ec_params_vbnvcontext *params; 69 struct cros_ec_command *msg; 70 int err; 71 const size_t para_sz = sizeof(*params); 72 const size_t data_sz = sizeof(params->block); 73 74 /* Only write full values */ 75 if (count != data_sz) 76 return -EINVAL; 77 78 msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL); 79 if (!msg) 80 return -ENOMEM; 81 82 params = (struct ec_params_vbnvcontext *)msg->data; 83 params->op = EC_VBNV_CONTEXT_OP_WRITE; 84 memcpy(params->block, buf, data_sz); 85 86 msg->version = EC_VER_VBNV_CONTEXT; 87 msg->command = EC_CMD_VBNV_CONTEXT; 88 msg->outsize = para_sz; 89 msg->insize = 0; 90 91 err = cros_ec_cmd_xfer_status(ecdev, msg); 92 if (err < 0) { 93 dev_err(dev, "Error sending write request: %d\n", err); 94 kfree(msg); 95 return err; 96 } 97 98 kfree(msg); 99 return data_sz; 100 } 101 102 static BIN_ATTR_RW(vboot_context, 16); 103 104 static struct bin_attribute *cros_ec_vbc_bin_attrs[] = { 105 &bin_attr_vboot_context, 106 NULL 107 }; 108 109 static const struct attribute_group cros_ec_vbc_attr_group = { 110 .name = "vbc", 111 .bin_attrs = cros_ec_vbc_bin_attrs, 112 }; 113 114 static int cros_ec_vbc_probe(struct platform_device *pd) 115 { 116 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 117 struct device *dev = &pd->dev; 118 int ret; 119 120 ret = sysfs_create_group(&ec_dev->class_dev.kobj, 121 &cros_ec_vbc_attr_group); 122 if (ret < 0) 123 dev_err(dev, "failed to create %s attributes. err=%d\n", 124 cros_ec_vbc_attr_group.name, ret); 125 126 return ret; 127 } 128 129 static void cros_ec_vbc_remove(struct platform_device *pd) 130 { 131 struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent); 132 133 sysfs_remove_group(&ec_dev->class_dev.kobj, 134 &cros_ec_vbc_attr_group); 135 } 136 137 static const struct platform_device_id cros_ec_vbc_id[] = { 138 { DRV_NAME, 0 }, 139 {} 140 }; 141 MODULE_DEVICE_TABLE(platform, cros_ec_vbc_id); 142 143 static struct platform_driver cros_ec_vbc_driver = { 144 .driver = { 145 .name = DRV_NAME, 146 }, 147 .probe = cros_ec_vbc_probe, 148 .remove_new = cros_ec_vbc_remove, 149 .id_table = cros_ec_vbc_id, 150 }; 151 152 module_platform_driver(cros_ec_vbc_driver); 153 154 MODULE_LICENSE("GPL"); 155 MODULE_DESCRIPTION("Expose the vboot context nvram to userspace"); 156