target/linux/generic/backport-5.10/809-v5.19-0006-nvmem-Add-Apple-eFuse-driver.patch

   1 From b6b7ef932ae838209254f016ecf8862d716a5ced Mon Sep 17 00:00:00 2001
   2 From: Sven Peter <sven@svenpeter.dev>
   3 Date: Fri, 29 Apr 2022 17:26:50 +0100
   4 Subject: [PATCH] nvmem: Add Apple eFuse driver
   5
   6 Apple SoCs contain eFuses used to store factory-programmed data such
   7 as calibration values for the PCIe or the Type-C PHY. They are organized
   8 as 32bit values exposed as MMIO.
   9
  10 Signed-off-by: Sven Peter <sven@svenpeter.dev>
  11 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  12 Link: https://lore.kernel.org/r/20220429162701.2222-6-srinivas.kandagatla@linaro.org
  13 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  14 ---
  15  drivers/nvmem/Kconfig        | 12 ++++++
  16  drivers/nvmem/Makefile       |  2 +
  17  drivers/nvmem/apple-efuses.c | 80 ++++++++++++++++++++++++++++++++++++
  18  3 files changed, 94 insertions(+)
  19  create mode 100644 drivers/nvmem/apple-efuses.c
  20
  21 --- a/drivers/nvmem/Kconfig
  22 +++ b/drivers/nvmem/Kconfig
  23 @@ -324,4 +324,16 @@ config NVMEM_SUNPLUS_OCOTP
  24           This driver can also be built as a module. If so, the module
  25           will be called nvmem-sunplus-ocotp.
  26
  27 +config NVMEM_APPLE_EFUSES
  28 +       tristate "Apple eFuse support"
  29 +       depends on ARCH_APPLE || COMPILE_TEST
  30 +       default ARCH_APPLE
  31 +       help
  32 +         Say y here to enable support for reading eFuses on Apple SoCs
  33 +         such as the M1. These are e.g. used to store factory programmed
  34 +         calibration data required for the PCIe or the USB-C PHY.
  35 +
  36 +         This driver can also be built as a module. If so, the module will
  37 +         be called nvmem-apple-efuses.
  38 +
  39  endif
  40 --- a/drivers/nvmem/Makefile
  41 +++ b/drivers/nvmem/Makefile
  42 @@ -65,3 +65,5 @@ obj-$(CONFIG_NVMEM_LAYERSCAPE_SFP)    += nv
  43  nvmem-layerscape-sfp-y         := layerscape-sfp.o
  44  obj-$(CONFIG_NVMEM_SUNPLUS_OCOTP)      += nvmem_sunplus_ocotp.o
  45  nvmem_sunplus_ocotp-y          := sunplus-ocotp.o
  46 +obj-$(CONFIG_NVMEM_APPLE_EFUSES)       += nvmem-apple-efuses.o
  47 +nvmem-apple-efuses-y           := apple-efuses.o
  48 --- /dev/null
  49 +++ b/drivers/nvmem/apple-efuses.c
  50 @@ -0,0 +1,80 @@
  51 +// SPDX-License-Identifier: GPL-2.0-only
  52 +/*
  53 + * Apple SoC eFuse driver
  54 + *
  55 + * Copyright (C) The Asahi Linux Contributors
  56 + */
  57 +
  58 +#include <linux/io.h>
  59 +#include <linux/mod_devicetable.h>
  60 +#include <linux/module.h>
  61 +#include <linux/nvmem-provider.h>
  62 +#include <linux/platform_device.h>
  63 +
  64 +struct apple_efuses_priv {
  65 +       void __iomem *fuses;
  66 +};
  67 +
  68 +static int apple_efuses_read(void *context, unsigned int offset, void *val,
  69 +                            size_t bytes)
  70 +{
  71 +       struct apple_efuses_priv *priv = context;
  72 +       u32 *dst = val;
  73 +
  74 +       while (bytes >= sizeof(u32)) {
  75 +               *dst++ = readl_relaxed(priv->fuses + offset);
  76 +               bytes -= sizeof(u32);
  77 +               offset += sizeof(u32);
  78 +       }
  79 +
  80 +       return 0;
  81 +}
  82 +
  83 +static int apple_efuses_probe(struct platform_device *pdev)
  84 +{
  85 +       struct apple_efuses_priv *priv;
  86 +       struct resource *res;
  87 +       struct nvmem_config config = {
  88 +               .dev = &pdev->dev,
  89 +               .read_only = true,
  90 +               .reg_read = apple_efuses_read,
  91 +               .stride = sizeof(u32),
  92 +               .word_size = sizeof(u32),
  93 +               .name = "apple_efuses_nvmem",
  94 +               .id = NVMEM_DEVID_AUTO,
  95 +               .root_only = true,
  96 +       };
  97 +
  98 +       priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
  99 +       if (!priv)
 100 +               return -ENOMEM;
 101 +
 102 +       priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 103 +       if (IS_ERR(priv->fuses))
 104 +               return PTR_ERR(priv->fuses);
 105 +
 106 +       config.priv = priv;
 107 +       config.size = resource_size(res);
 108 +
 109 +       return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
 110 +}
 111 +
 112 +static const struct of_device_id apple_efuses_of_match[] = {
 113 +       { .compatible = "apple,efuses", },
 114 +       {}
 115 +};
 116 +
 117 +MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
 118 +
 119 +static struct platform_driver apple_efuses_driver = {
 120 +       .driver = {
 121 +               .name = "apple_efuses",
 122 +               .of_match_table = apple_efuses_of_match,
 123 +       },
 124 +       .probe = apple_efuses_probe,
 125 +};
 126 +
 127 +module_platform_driver(apple_efuses_driver);
 128 +
 129 +MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
 130 +MODULE_LICENSE("GPL");