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Message-Id: <20210304144132.24098-2-zajec5@gmail.com>
Date: Thu, 4 Mar 2021 15:41:32 +0100
From: Rafał Miłecki <zajec5@...il.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Rob Herring <robh+dt@...nel.org>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mips@...r.kernel.org,
Florian Fainelli <f.fainelli@...il.com>,
Vivek Unune <npcomplete13@...il.com>,
bcm-kernel-feedback-list@...adcom.com,
linux-kernel@...r.kernel.org,
Rafał Miłecki <rafal@...ecki.pl>
Subject: [PATCH 2/2] nvmem: iomap: new driver exposing NVMEM accessible using I/O mapping
From: Rafał Miłecki <rafal@...ecki.pl>
This is a generic NVMEM access method used e.g. by Broadcom for their
NVRAM on MIPS and Northstar devices.
Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
---
drivers/nvmem/Kconfig | 7 +++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/iomap.c | 99 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 108 insertions(+)
create mode 100644 drivers/nvmem/iomap.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 75d2594c16e1..3d5c5684685d 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -278,4 +278,11 @@ config NVMEM_RMEM
This driver can also be built as a module. If so, the module
will be called nvmem-rmem.
+
+config NVMEM_IOMAP
+ tristate "I/O mapped NVMEM support"
+ depends on HAS_IOMEM
+ help
+ This driver supports NVMEM that can be accessed using I/O mapping.
+
endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 5376b8e0dae5..88a3b6979c53 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -57,3 +57,5 @@ obj-$(CONFIG_SPRD_EFUSE) += nvmem_sprd_efuse.o
nvmem_sprd_efuse-y := sprd-efuse.o
obj-$(CONFIG_NVMEM_RMEM) += nvmem-rmem.o
nvmem-rmem-y := rmem.o
+obj-$(CONFIG_NVMEM_IOMAP) += nvmem_iomap.o
+nvmem_iomap-y := iomap.o
diff --git a/drivers/nvmem/iomap.c b/drivers/nvmem/iomap.c
new file mode 100644
index 000000000000..ab6b40858a64
--- /dev/null
+++ b/drivers/nvmem/iomap.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal@...ecki.pl>
+ */
+
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+
+struct iomap {
+ struct device *dev;
+ void __iomem *base;
+};
+
+static int iomap_read(void *context, unsigned int offset, void *val,
+ size_t bytes)
+{
+ struct iomap *priv = context;
+ u8 *src = priv->base + offset;
+ u8 *dst = val;
+ size_t tmp;
+
+ tmp = offset % 4;
+ memcpy_fromio(dst, src, tmp);
+ dst += tmp;
+ src += tmp;
+ bytes -= tmp;
+
+ tmp = rounddown(bytes, 4);
+ __ioread32_copy(dst, src, tmp / 4);
+ dst += tmp;
+ src += tmp;
+ bytes -= tmp;
+
+ memcpy_fromio(dst, src, bytes);
+
+ return 0;
+}
+
+static int iomap_probe(struct platform_device *pdev)
+{
+ struct nvmem_config config = {
+ .name = "iomap",
+ .reg_read = iomap_read,
+ };
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ struct iomap *priv;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+ priv->dev = dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(dev, "Failed to get resource\n");
+ return -ENODEV;
+ }
+
+ priv->base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(priv->base)) {
+ dev_err(dev, "Failed to map resource: %ld\n", PTR_ERR(priv->base));
+ return PTR_ERR(priv->base);
+ }
+
+ config.dev = dev;
+ config.priv = priv;
+ config.size = resource_size(res);
+
+ return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+}
+
+static const struct of_device_id iomap_of_match_table[] = {
+ { .compatible = "brcm,nvram", },
+ { .compatible = "nvmem-iomap", },
+ {},
+};
+
+static struct platform_driver iomap_driver = {
+ .probe = iomap_probe,
+ .driver = {
+ .name = "nvmem_iomap",
+ .of_match_table = iomap_of_match_table,
+ },
+};
+
+static int __init iomap_init(void)
+{
+ return platform_driver_register(&iomap_driver);
+}
+
+subsys_initcall_sync(iomap_init);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL v2");
+MODULE_DEVICE_TABLE(of, iomap_of_match_table);
--
2.26.2
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