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131 lines
3.7 KiB
Diff
131 lines
3.7 KiB
Diff
From b6b7ef932ae838209254f016ecf8862d716a5ced Mon Sep 17 00:00:00 2001
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From: Sven Peter <sven@svenpeter.dev>
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Date: Fri, 29 Apr 2022 17:26:50 +0100
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Subject: [PATCH] nvmem: Add Apple eFuse driver
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Apple SoCs contain eFuses used to store factory-programmed data such
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as calibration values for the PCIe or the Type-C PHY. They are organized
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as 32bit values exposed as MMIO.
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Signed-off-by: Sven Peter <sven@svenpeter.dev>
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Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
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Link: https://lore.kernel.org/r/20220429162701.2222-6-srinivas.kandagatla@linaro.org
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/nvmem/Kconfig | 12 ++++++
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drivers/nvmem/Makefile | 2 +
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drivers/nvmem/apple-efuses.c | 80 ++++++++++++++++++++++++++++++++++++
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3 files changed, 94 insertions(+)
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create mode 100644 drivers/nvmem/apple-efuses.c
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--- a/drivers/nvmem/Kconfig
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+++ b/drivers/nvmem/Kconfig
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@@ -324,4 +324,16 @@ config NVMEM_SUNPLUS_OCOTP
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This driver can also be built as a module. If so, the module
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will be called nvmem-sunplus-ocotp.
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+config NVMEM_APPLE_EFUSES
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+ tristate "Apple eFuse support"
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+ depends on ARCH_APPLE || COMPILE_TEST
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+ default ARCH_APPLE
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+ help
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+ Say y here to enable support for reading eFuses on Apple SoCs
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+ such as the M1. These are e.g. used to store factory programmed
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+ calibration data required for the PCIe or the USB-C PHY.
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+
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+ This driver can also be built as a module. If so, the module will
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+ be called nvmem-apple-efuses.
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+
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endif
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--- a/drivers/nvmem/Makefile
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+++ b/drivers/nvmem/Makefile
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@@ -65,3 +65,5 @@ obj-$(CONFIG_NVMEM_LAYERSCAPE_SFP) += nv
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nvmem-layerscape-sfp-y := layerscape-sfp.o
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obj-$(CONFIG_NVMEM_SUNPLUS_OCOTP) += nvmem_sunplus_ocotp.o
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nvmem_sunplus_ocotp-y := sunplus-ocotp.o
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+obj-$(CONFIG_NVMEM_APPLE_EFUSES) += nvmem-apple-efuses.o
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+nvmem-apple-efuses-y := apple-efuses.o
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--- /dev/null
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+++ b/drivers/nvmem/apple-efuses.c
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@@ -0,0 +1,80 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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+/*
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+ * Apple SoC eFuse driver
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+ *
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+ * Copyright (C) The Asahi Linux Contributors
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+ */
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+
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+#include <linux/io.h>
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+#include <linux/mod_devicetable.h>
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+#include <linux/module.h>
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+#include <linux/nvmem-provider.h>
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+#include <linux/platform_device.h>
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+
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+struct apple_efuses_priv {
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+ void __iomem *fuses;
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+};
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+
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+static int apple_efuses_read(void *context, unsigned int offset, void *val,
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+ size_t bytes)
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+{
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+ struct apple_efuses_priv *priv = context;
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+ u32 *dst = val;
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+
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+ while (bytes >= sizeof(u32)) {
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+ *dst++ = readl_relaxed(priv->fuses + offset);
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+ bytes -= sizeof(u32);
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+ offset += sizeof(u32);
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+ }
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+
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+ return 0;
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+}
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+
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+static int apple_efuses_probe(struct platform_device *pdev)
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+{
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+ struct apple_efuses_priv *priv;
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+ struct resource *res;
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+ struct nvmem_config config = {
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+ .dev = &pdev->dev,
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+ .read_only = true,
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+ .reg_read = apple_efuses_read,
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+ .stride = sizeof(u32),
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+ .word_size = sizeof(u32),
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+ .name = "apple_efuses_nvmem",
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+ .id = NVMEM_DEVID_AUTO,
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+ .root_only = true,
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+ };
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+
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+ priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
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+ if (!priv)
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+ return -ENOMEM;
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+
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+ priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
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+ if (IS_ERR(priv->fuses))
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+ return PTR_ERR(priv->fuses);
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+
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+ config.priv = priv;
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+ config.size = resource_size(res);
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+
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+ return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
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+}
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+
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+static const struct of_device_id apple_efuses_of_match[] = {
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+ { .compatible = "apple,efuses", },
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+ {}
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+};
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+
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+MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
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+
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+static struct platform_driver apple_efuses_driver = {
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+ .driver = {
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+ .name = "apple_efuses",
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+ .of_match_table = apple_efuses_of_match,
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+ },
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+ .probe = apple_efuses_probe,
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+};
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+
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+module_platform_driver(apple_efuses_driver);
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+
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+MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
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+MODULE_LICENSE("GPL");
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