On 01/02/2023 06:47, Rafał Miłecki wrote:
From: Rafał Miłecki <rafal@xxxxxxxxxx>
With nvmem layouts in place we should now work on plain content access
NVMEM drivers (e.g. MMIO one). Actual NVMEM content handling should go
to layout drivers.
Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
---
drivers/nvmem/Kconfig | 10 ++++++
drivers/nvmem/Makefile | 2 ++
drivers/nvmem/mmio.c | 80 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 92 insertions(+)
create mode 100644 drivers/nvmem/mmio.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 789729ff7e50..9eb5e93f0455 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -170,6 +170,16 @@ 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 442f9a4876a5..2f2bed7cdf24 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -36,6 +36,8 @@ 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..19c8880dc675
--- /dev/null
+++ b/drivers/nvmem/mmio.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Rafał Miłecki <rafal@xxxxxxxxxx>
+ */
+
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+struct mmio_nvmem {
+ void __iomem *base;
+};
+
+static int mmio_nvmem_read(void *context, unsigned int offset, void *val, size_t bytes)
+{
+ struct mmio_nvmem *priv = context;
+
+ memcpy_fromio(val, priv->base, bytes);
How does this work with different register strides?
+
+ return 0;
+}
+
+static int mmio_nvmem_probe(struct platform_device *pdev)
+{
+ struct nvmem_config config = {
+ .name = "mmio-nvmem",
you could use NVMEM_DEVID_AUTO.
But this is not great, this is going to break the existing abi for
converted drivers. Either we find a way to pass compatible specific data
and override the default values.
Also there are going to be cases where access to registers will require
additional resources like clks or pd.
--srini
+ .read_only = true,
+ .reg_read = mmio_nvmem_read,
+ };
+ 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);
+
+ config.dev = dev;
+ config.size = resource_size(res);
+ config.word_size = sizeof(u8);
+ config.stride = sizeof(u8);
+ config.priv = priv;
+
+ if (!device_property_present(dev, "read-only"))
+ dev_warn(dev, "Writing is not supported yet");
+
+ 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);
