1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * ARM System Control and Management Interface (ARM SCMI) reset driver 4 * 5 * Copyright (C) 2019-2021 ARM Ltd. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/of.h> 10 #include <linux/device.h> 11 #include <linux/reset-controller.h> 12 #include <linux/scmi_protocol.h> 13 14 static const struct scmi_reset_proto_ops *reset_ops; 15 16 /** 17 * struct scmi_reset_data - reset controller information structure 18 * @rcdev: reset controller entity 19 * @ph: ARM SCMI protocol handle used for communication with system controller 20 */ 21 struct scmi_reset_data { 22 struct reset_controller_dev rcdev; 23 const struct scmi_protocol_handle *ph; 24 }; 25 26 #define to_scmi_reset_data(p) container_of((p), struct scmi_reset_data, rcdev) 27 #define to_scmi_handle(p) (to_scmi_reset_data(p)->ph) 28 29 /** 30 * scmi_reset_assert() - assert device reset 31 * @rcdev: reset controller entity 32 * @id: ID of the reset to be asserted 33 * 34 * This function implements the reset driver op to assert a device's reset 35 * using the ARM SCMI protocol. 36 * 37 * Return: 0 for successful request, else a corresponding error value 38 */ 39 static int 40 scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id) 41 { 42 const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev); 43 44 return reset_ops->assert(ph, id); 45 } 46 47 /** 48 * scmi_reset_deassert() - deassert device reset 49 * @rcdev: reset controller entity 50 * @id: ID of the reset to be deasserted 51 * 52 * This function implements the reset driver op to deassert a device's reset 53 * using the ARM SCMI protocol. 54 * 55 * Return: 0 for successful request, else a corresponding error value 56 */ 57 static int 58 scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id) 59 { 60 const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev); 61 62 return reset_ops->deassert(ph, id); 63 } 64 65 /** 66 * scmi_reset_reset() - reset the device 67 * @rcdev: reset controller entity 68 * @id: ID of the reset signal to be reset(assert + deassert) 69 * 70 * This function implements the reset driver op to trigger a device's 71 * reset signal using the ARM SCMI protocol. 72 * 73 * Return: 0 for successful request, else a corresponding error value 74 */ 75 static int 76 scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id) 77 { 78 const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev); 79 80 return reset_ops->reset(ph, id); 81 } 82 83 static const struct reset_control_ops scmi_reset_ops = { 84 .assert = scmi_reset_assert, 85 .deassert = scmi_reset_deassert, 86 .reset = scmi_reset_reset, 87 }; 88 89 static int scmi_reset_probe(struct scmi_device *sdev) 90 { 91 struct scmi_reset_data *data; 92 struct device *dev = &sdev->dev; 93 struct device_node *np = dev->of_node; 94 const struct scmi_handle *handle = sdev->handle; 95 struct scmi_protocol_handle *ph; 96 97 if (!handle) 98 return -ENODEV; 99 100 reset_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_RESET, &ph); 101 if (IS_ERR(reset_ops)) 102 return PTR_ERR(reset_ops); 103 104 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 105 if (!data) 106 return -ENOMEM; 107 108 data->rcdev.ops = &scmi_reset_ops; 109 data->rcdev.owner = THIS_MODULE; 110 data->rcdev.of_node = np; 111 data->rcdev.nr_resets = reset_ops->num_domains_get(ph); 112 data->ph = ph; 113 114 return devm_reset_controller_register(dev, &data->rcdev); 115 } 116 117 static const struct scmi_device_id scmi_id_table[] = { 118 { SCMI_PROTOCOL_RESET, "reset" }, 119 { }, 120 }; 121 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 122 123 static struct scmi_driver scmi_reset_driver = { 124 .name = "scmi-reset", 125 .probe = scmi_reset_probe, 126 .id_table = scmi_id_table, 127 }; 128 module_scmi_driver(scmi_reset_driver); 129 130 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 131 MODULE_DESCRIPTION("ARM SCMI reset controller driver"); 132 MODULE_LICENSE("GPL v2"); 133