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Message-Id: <20230228072936.1108-3-zajec5@gmail.com>
Date: Tue, 28 Feb 2023 08:29:36 +0100
From: Rafał Miłecki <zajec5@...il.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc: Matthias Brugger <matthias.bgg@...il.com>,
Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
linux-mediatek@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
Rafał Miłecki <rafal@...ecki.pl>
Subject: [PATCH V4 2/2] nvmem: add generic driver for devices with MMIO access
From: Rafał Miłecki <rafal@...ecki.pl>
Some NVMEM devices can be accessed by simply mapping memory and reading
from / writing to it. This driver adds support for a generic
"mmio-nvmem" DT binding used by such devices.
One of such devices is Broadcom's NVRAM. It's already supported (see
NVMEM_BRCM_NVRAM) but existing driver covers both:
1. NVMEM device access
2. NVMEM content parsing
Once we get support for NVMEM layouts then existing NVRAM driver will
get converted into a layout and generic driver will take over
responsibility for data access.
Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
---
V3: Support "reg-io-width", basic writing & "brcm,nvram" string
V3: Don't duplicate core checks, add 64 b support, complete writing
support, don't add confusing conditional "brcm,nvram" support (it
will be handled with layouts migration)
---
drivers/nvmem/Kconfig | 10 +++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/mmio.c | 148 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 160 insertions(+)
create mode 100644 drivers/nvmem/mmio.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 6dec38805041..189ea85bd67d 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -166,6 +166,16 @@ config NVMEM_MICROCHIP_OTPC
This driver enable the OTP controller available on Microchip SAMA7G5
SoCs. It controls the access to the OTP memory connected to it.
+config NVMEM_MMIO
+ tristate "MMIO access based NVMEM support"
+ depends on HAS_IOMEM
+ help
+ This driver provides support for NVMEM devices that can be accessed
+ using MMIO.
+
+ This driver can also be built as a module. If so, the module
+ will be called nvmem-mmio.
+
config NVMEM_MTK_EFUSE
tristate "Mediatek SoCs EFUSE support"
depends on ARCH_MEDIATEK || COMPILE_TEST
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 6a1efffa88f0..767a9db2bfc1 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -35,6 +35,8 @@ obj-$(CONFIG_NVMEM_MESON_MX_EFUSE) += nvmem_meson_mx_efuse.o
nvmem_meson_mx_efuse-y := meson-mx-efuse.o
obj-$(CONFIG_NVMEM_MICROCHIP_OTPC) += nvmem-microchip-otpc.o
nvmem-microchip-otpc-y := microchip-otpc.o
+obj-$(CONFIG_NVMEM_MMIO) += nvmem-mmio.o
+nvmem-mmio-y := mmio.o
obj-$(CONFIG_NVMEM_MTK_EFUSE) += nvmem_mtk-efuse.o
nvmem_mtk-efuse-y := mtk-efuse.o
obj-$(CONFIG_NVMEM_MXS_OCOTP) += nvmem-mxs-ocotp.o
diff --git a/drivers/nvmem/mmio.c b/drivers/nvmem/mmio.c
new file mode 100644
index 000000000000..ce51648bb321
--- /dev/null
+++ b/drivers/nvmem/mmio.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 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/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+struct mmio_nvmem {
+ void __iomem *base;
+ u32 io_width;
+};
+
+static int mmio_nvmem_read(void *context, unsigned int offset, void *val, size_t bytes)
+{
+ struct mmio_nvmem *priv = context;
+ u64 __maybe_unused *dst64;
+ u32 *dst32;
+ u16 *dst16;
+ u8 *dst8;
+
+ switch (priv->io_width) {
+ case 0:
+ memcpy_fromio(val, priv->base + offset, bytes);
+ break;
+ case 1:
+ for (dst8 = val; bytes; bytes -= 1, offset += 1)
+ *dst8++ = readb(priv->base + offset);
+ break;
+ case 2:
+ for (dst16 = val; bytes; bytes -= 2, offset += 2)
+ *dst16++ = readw(priv->base + offset);
+ break;
+ case 4:
+ for (dst32 = val; bytes; bytes -= 4, offset += 4)
+ *dst32++ = readl(priv->base + offset);
+ break;
+#ifdef CONFIG_64BIT
+ case 8:
+ for (dst64 = val; bytes; bytes -= 8, offset += 8)
+ *dst64++ = readq(priv->base + offset);
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int mmio_nvmem_write(void *context, unsigned int offset, void *val, size_t bytes)
+{
+ struct mmio_nvmem *priv = context;
+ u64 __maybe_unused *dst64;
+ u32 *dst32;
+ u16 *dst16;
+ u8 *dst8;
+
+ switch (priv->io_width) {
+ case 0:
+ memcpy_toio(priv->base + offset, val, bytes);
+ break;
+ case 1:
+ for (dst8 = val; bytes; bytes -= 1, offset += 1)
+ writeb(*dst8++, priv->base + offset);
+ break;
+ case 2:
+ for (dst16 = val; bytes; bytes -= 2, offset += 2)
+ writew(*dst16++, priv->base + offset);
+ break;
+ case 4:
+ for (dst32 = val; bytes; bytes -= 4, offset += 4)
+ writel(*dst32++, priv->base + offset);
+ break;
+#ifdef CONFIG_64BIT
+ case 8:
+ for (dst64 = val; bytes; bytes -= 8, offset += 8)
+ writeq(*dst64++, priv->base + offset);
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int mmio_nvmem_probe(struct platform_device *pdev)
+{
+ struct nvmem_config config = {
+ .name = "mmio-nvmem",
+ .id = NVMEM_DEVID_AUTO,
+ .read_only = true,
+ .reg_read = mmio_nvmem_read,
+ .reg_write = mmio_nvmem_write,
+ };
+ struct device *dev = &pdev->dev;
+ struct mmio_nvmem *priv;
+ struct resource *res;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ of_property_read_u32(dev->of_node, "reg-io-width", &priv->io_width);
+
+ config.dev = dev;
+ config.size = resource_size(res);
+ config.word_size = priv->io_width;
+ config.stride = priv->io_width;
+ config.priv = priv;
+
+ return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+}
+
+static const struct of_device_id mmio_nvmem_of_match_table[] = {
+ { .compatible = "mmio-nvmem", },
+ {},
+};
+
+static struct platform_driver mmio_nvmem_driver = {
+ .probe = mmio_nvmem_probe,
+ .driver = {
+ .name = "mmio_nvmem",
+ .of_match_table = mmio_nvmem_of_match_table,
+ },
+};
+
+static int __init mmio_nvmem_init(void)
+{
+ return platform_driver_register(&mmio_nvmem_driver);
+}
+
+subsys_initcall_sync(mmio_nvmem_init);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, mmio_nvmem_of_match_table);
--
2.34.1
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