1 // SPDX-License-Identifier: GPL-2.0-only 2 // 3 // Copyright 2020 Google Inc 4 // Copyright 2025 Linaro Ltd. 5 // 6 // NVMEM driver for Maxim MAX77759 7 8 #include <linux/dev_printk.h> 9 #include <linux/device.h> 10 #include <linux/device/driver.h> 11 #include <linux/err.h> 12 #include <linux/mfd/max77759.h> 13 #include <linux/mod_devicetable.h> 14 #include <linux/module.h> 15 #include <linux/nvmem-provider.h> 16 #include <linux/overflow.h> 17 #include <linux/platform_device.h> 18 #include <linux/string.h> 19 20 #define MAX77759_NVMEM_OPCODE_HEADER_LEN 3 21 /* 22 * NVMEM commands have a three byte header (which becomes part of the command), 23 * so we need to subtract that. 24 */ 25 #define MAX77759_NVMEM_SIZE (MAX77759_MAXQ_OPCODE_MAXLENGTH \ 26 - MAX77759_NVMEM_OPCODE_HEADER_LEN) 27 28 struct max77759_nvmem { 29 struct device *dev; 30 struct max77759 *max77759; 31 }; 32 33 static int max77759_nvmem_reg_read(void *priv, unsigned int offset, 34 void *val, size_t bytes) 35 { 36 struct max77759_nvmem *nvmem = priv; 37 DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length, 38 MAX77759_NVMEM_OPCODE_HEADER_LEN); 39 DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length, 40 MAX77759_MAXQ_OPCODE_MAXLENGTH); 41 int ret; 42 43 cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_READ; 44 cmd->cmd[1] = offset; 45 cmd->cmd[2] = bytes; 46 rsp->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN; 47 48 ret = max77759_maxq_command(nvmem->max77759, cmd, rsp); 49 if (ret < 0) 50 return ret; 51 52 if (memcmp(cmd->cmd, rsp->rsp, MAX77759_NVMEM_OPCODE_HEADER_LEN)) { 53 dev_warn(nvmem->dev, "protocol error (read)\n"); 54 return -EIO; 55 } 56 57 memcpy(val, &rsp->rsp[MAX77759_NVMEM_OPCODE_HEADER_LEN], bytes); 58 59 return 0; 60 } 61 62 static int max77759_nvmem_reg_write(void *priv, unsigned int offset, 63 void *val, size_t bytes) 64 { 65 struct max77759_nvmem *nvmem = priv; 66 DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length, 67 MAX77759_MAXQ_OPCODE_MAXLENGTH); 68 DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length, 69 MAX77759_MAXQ_OPCODE_MAXLENGTH); 70 int ret; 71 72 cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_WRITE; 73 cmd->cmd[1] = offset; 74 cmd->cmd[2] = bytes; 75 memcpy(&cmd->cmd[MAX77759_NVMEM_OPCODE_HEADER_LEN], val, bytes); 76 cmd->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN; 77 rsp->length = cmd->length; 78 79 ret = max77759_maxq_command(nvmem->max77759, cmd, rsp); 80 if (ret < 0) 81 return ret; 82 83 if (memcmp(cmd->cmd, rsp->rsp, cmd->length)) { 84 dev_warn(nvmem->dev, "protocol error (write)\n"); 85 return -EIO; 86 } 87 88 return 0; 89 } 90 91 static int max77759_nvmem_probe(struct platform_device *pdev) 92 { 93 struct nvmem_config config = { 94 .dev = &pdev->dev, 95 .name = dev_name(&pdev->dev), 96 .id = NVMEM_DEVID_NONE, 97 .type = NVMEM_TYPE_EEPROM, 98 .ignore_wp = true, 99 .size = MAX77759_NVMEM_SIZE, 100 .word_size = sizeof(u8), 101 .stride = sizeof(u8), 102 .reg_read = max77759_nvmem_reg_read, 103 .reg_write = max77759_nvmem_reg_write, 104 }; 105 struct max77759_nvmem *nvmem; 106 107 nvmem = devm_kzalloc(&pdev->dev, sizeof(*nvmem), GFP_KERNEL); 108 if (!nvmem) 109 return -ENOMEM; 110 111 nvmem->dev = &pdev->dev; 112 nvmem->max77759 = dev_get_drvdata(pdev->dev.parent); 113 114 config.priv = nvmem; 115 116 return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config)); 117 } 118 119 static const struct of_device_id max77759_nvmem_of_id[] = { 120 { .compatible = "maxim,max77759-nvmem", }, 121 { } 122 }; 123 MODULE_DEVICE_TABLE(of, max77759_nvmem_of_id); 124 125 static const struct platform_device_id max77759_nvmem_platform_id[] = { 126 { "max77759-nvmem", }, 127 { } 128 }; 129 MODULE_DEVICE_TABLE(platform, max77759_nvmem_platform_id); 130 131 static struct platform_driver max77759_nvmem_driver = { 132 .driver = { 133 .name = "max77759-nvmem", 134 .probe_type = PROBE_PREFER_ASYNCHRONOUS, 135 .of_match_table = max77759_nvmem_of_id, 136 }, 137 .probe = max77759_nvmem_probe, 138 .id_table = max77759_nvmem_platform_id, 139 }; 140 141 module_platform_driver(max77759_nvmem_driver); 142 143 MODULE_AUTHOR("André Draszik <andre.draszik@linaro.org>"); 144 MODULE_DESCRIPTION("NVMEM driver for Maxim MAX77759"); 145 MODULE_LICENSE("GPL"); 146