1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * NXP LPC18xx/43xx OTP memory NVMEM driver 4 * 5 * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com> 6 * 7 * Based on the imx ocotp driver, 8 * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de> 9 * 10 * TODO: add support for writing OTP register via API in boot ROM. 11 */ 12 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/nvmem-provider.h> 16 #include <linux/of.h> 17 #include <linux/platform_device.h> 18 #include <linux/slab.h> 19 20 /* 21 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts 22 * at offset 0 from the base. 23 * 24 * Bank 0 contains the part ID for Flashless devices and is reseverd for 25 * devices with Flash. 26 * Bank 1/2 is generale purpose or AES key storage for secure devices. 27 * Bank 3 contains control data, USB ID and generale purpose words. 28 */ 29 #define LPC18XX_OTP_NUM_BANKS 4 30 #define LPC18XX_OTP_WORDS_PER_BANK 4 31 #define LPC18XX_OTP_WORD_SIZE sizeof(u32) 32 #define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \ 33 LPC18XX_OTP_WORDS_PER_BANK * \ 34 LPC18XX_OTP_WORD_SIZE) 35 36 struct lpc18xx_otp { 37 void __iomem *base; 38 }; 39 40 static int lpc18xx_otp_read(void *context, unsigned int offset, 41 void *val, size_t bytes) 42 { 43 struct lpc18xx_otp *otp = context; 44 unsigned int count = bytes >> 2; 45 u32 index = offset >> 2; 46 u32 *buf = val; 47 int i; 48 49 if (count > (LPC18XX_OTP_SIZE - index)) 50 count = LPC18XX_OTP_SIZE - index; 51 52 for (i = index; i < (index + count); i++) 53 *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE); 54 55 return 0; 56 } 57 58 static struct nvmem_config lpc18xx_otp_nvmem_config = { 59 .name = "lpc18xx-otp", 60 .read_only = true, 61 .word_size = LPC18XX_OTP_WORD_SIZE, 62 .stride = LPC18XX_OTP_WORD_SIZE, 63 .reg_read = lpc18xx_otp_read, 64 }; 65 66 static int lpc18xx_otp_probe(struct platform_device *pdev) 67 { 68 struct nvmem_device *nvmem; 69 struct lpc18xx_otp *otp; 70 71 otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL); 72 if (!otp) 73 return -ENOMEM; 74 75 otp->base = devm_platform_ioremap_resource(pdev, 0); 76 if (IS_ERR(otp->base)) 77 return PTR_ERR(otp->base); 78 79 lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE; 80 lpc18xx_otp_nvmem_config.dev = &pdev->dev; 81 lpc18xx_otp_nvmem_config.priv = otp; 82 83 nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config); 84 85 return PTR_ERR_OR_ZERO(nvmem); 86 } 87 88 static const struct of_device_id lpc18xx_otp_dt_ids[] = { 89 { .compatible = "nxp,lpc1850-otp" }, 90 { }, 91 }; 92 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids); 93 94 static struct platform_driver lpc18xx_otp_driver = { 95 .probe = lpc18xx_otp_probe, 96 .driver = { 97 .name = "lpc18xx_otp", 98 .of_match_table = lpc18xx_otp_dt_ids, 99 }, 100 }; 101 module_platform_driver(lpc18xx_otp_driver); 102 103 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>"); 104 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver"); 105 MODULE_LICENSE("GPL v2"); 106