1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * sfr.c - driver for special function registers 4 * 5 * Copyright (C) 2019 Bootlin. 6 * 7 */ 8 #include <linux/mfd/syscon.h> 9 #include <linux/module.h> 10 #include <linux/nvmem-provider.h> 11 #include <linux/random.h> 12 #include <linux/of.h> 13 #include <linux/of_device.h> 14 #include <linux/platform_device.h> 15 #include <linux/regmap.h> 16 17 #define SFR_SN0 0x4c 18 #define SFR_SN_SIZE 8 19 20 struct atmel_sfr_priv { 21 struct regmap *regmap; 22 }; 23 24 static int atmel_sfr_read(void *context, unsigned int offset, 25 void *buf, size_t bytes) 26 { 27 struct atmel_sfr_priv *priv = context; 28 29 return regmap_bulk_read(priv->regmap, SFR_SN0 + offset, 30 buf, bytes / 4); 31 } 32 33 static struct nvmem_config atmel_sfr_nvmem_config = { 34 .name = "atmel-sfr", 35 .read_only = true, 36 .word_size = 4, 37 .stride = 4, 38 .size = SFR_SN_SIZE, 39 .reg_read = atmel_sfr_read, 40 }; 41 42 static int atmel_sfr_probe(struct platform_device *pdev) 43 { 44 struct device *dev = &pdev->dev; 45 struct device_node *np = dev->of_node; 46 struct nvmem_device *nvmem; 47 struct atmel_sfr_priv *priv; 48 u8 sn[SFR_SN_SIZE]; 49 int ret; 50 51 priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL); 52 if (!priv) 53 return -ENOMEM; 54 55 priv->regmap = syscon_node_to_regmap(np); 56 if (IS_ERR(priv->regmap)) { 57 dev_err(dev, "cannot get parent's regmap\n"); 58 return PTR_ERR(priv->regmap); 59 } 60 61 atmel_sfr_nvmem_config.dev = dev; 62 atmel_sfr_nvmem_config.priv = priv; 63 64 nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config); 65 if (IS_ERR(nvmem)) { 66 dev_err(dev, "error registering nvmem config\n"); 67 return PTR_ERR(nvmem); 68 } 69 70 ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE); 71 if (ret == 0) 72 add_device_randomness(sn, SFR_SN_SIZE); 73 74 return ret; 75 } 76 77 static const struct of_device_id atmel_sfr_dt_ids[] = { 78 { 79 .compatible = "atmel,sama5d2-sfr", 80 }, { 81 .compatible = "atmel,sama5d4-sfr", 82 }, { 83 /* sentinel */ 84 }, 85 }; 86 MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids); 87 88 static struct platform_driver atmel_sfr_driver = { 89 .probe = atmel_sfr_probe, 90 .driver = { 91 .name = "atmel-sfr", 92 .of_match_table = atmel_sfr_dt_ids, 93 }, 94 }; 95 module_platform_driver(atmel_sfr_driver); 96 97 MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>"); 98 MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family"); 99 MODULE_LICENSE("GPL v2"); 100