1 /* 2 * NXP LPC18xx/43xx OTP memory NVMEM driver 3 * 4 * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com> 5 * 6 * Based on the imx ocotp driver, 7 * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation. 12 * 13 * TODO: add support for writing OTP register via API in boot ROM. 14 */ 15 16 #include <linux/io.h> 17 #include <linux/module.h> 18 #include <linux/nvmem-provider.h> 19 #include <linux/of.h> 20 #include <linux/of_device.h> 21 #include <linux/platform_device.h> 22 #include <linux/slab.h> 23 24 /* 25 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts 26 * at offset 0 from the base. 27 * 28 * Bank 0 contains the part ID for Flashless devices and is reseverd for 29 * devices with Flash. 30 * Bank 1/2 is generale purpose or AES key storage for secure devices. 31 * Bank 3 contains control data, USB ID and generale purpose words. 32 */ 33 #define LPC18XX_OTP_NUM_BANKS 4 34 #define LPC18XX_OTP_WORDS_PER_BANK 4 35 #define LPC18XX_OTP_WORD_SIZE sizeof(u32) 36 #define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \ 37 LPC18XX_OTP_WORDS_PER_BANK * \ 38 LPC18XX_OTP_WORD_SIZE) 39 40 struct lpc18xx_otp { 41 void __iomem *base; 42 }; 43 44 static int lpc18xx_otp_read(void *context, unsigned int offset, 45 void *val, size_t bytes) 46 { 47 struct lpc18xx_otp *otp = context; 48 unsigned int count = bytes >> 2; 49 u32 index = offset >> 2; 50 u32 *buf = val; 51 int i; 52 53 if (count > (LPC18XX_OTP_SIZE - index)) 54 count = LPC18XX_OTP_SIZE - index; 55 56 for (i = index; i < (index + count); i++) 57 *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE); 58 59 return 0; 60 } 61 62 static struct nvmem_config lpc18xx_otp_nvmem_config = { 63 .name = "lpc18xx-otp", 64 .read_only = true, 65 .word_size = LPC18XX_OTP_WORD_SIZE, 66 .stride = LPC18XX_OTP_WORD_SIZE, 67 .owner = THIS_MODULE, 68 .reg_read = lpc18xx_otp_read, 69 }; 70 71 static int lpc18xx_otp_probe(struct platform_device *pdev) 72 { 73 struct nvmem_device *nvmem; 74 struct lpc18xx_otp *otp; 75 struct resource *res; 76 77 otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL); 78 if (!otp) 79 return -ENOMEM; 80 81 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 82 otp->base = devm_ioremap_resource(&pdev->dev, res); 83 if (IS_ERR(otp->base)) 84 return PTR_ERR(otp->base); 85 86 lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE; 87 lpc18xx_otp_nvmem_config.dev = &pdev->dev; 88 lpc18xx_otp_nvmem_config.priv = otp; 89 90 nvmem = nvmem_register(&lpc18xx_otp_nvmem_config); 91 if (IS_ERR(nvmem)) 92 return PTR_ERR(nvmem); 93 94 platform_set_drvdata(pdev, nvmem); 95 96 return 0; 97 } 98 99 static int lpc18xx_otp_remove(struct platform_device *pdev) 100 { 101 struct nvmem_device *nvmem = platform_get_drvdata(pdev); 102 103 return nvmem_unregister(nvmem); 104 } 105 106 static const struct of_device_id lpc18xx_otp_dt_ids[] = { 107 { .compatible = "nxp,lpc1850-otp" }, 108 { }, 109 }; 110 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids); 111 112 static struct platform_driver lpc18xx_otp_driver = { 113 .probe = lpc18xx_otp_probe, 114 .remove = lpc18xx_otp_remove, 115 .driver = { 116 .name = "lpc18xx_otp", 117 .of_match_table = lpc18xx_otp_dt_ids, 118 }, 119 }; 120 module_platform_driver(lpc18xx_otp_driver); 121 122 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>"); 123 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver"); 124 MODULE_LICENSE("GPL v2"); 125