On 05.03.2021 11:02, Srinivas Kandagatla wrote:

On 04/03/2021 14:41, Rafał Miłecki wrote:

quoted

From: Rafał Miłecki <rafal@milecki.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@milecki.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@milecki.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);
+

You could just do this!

     while (bytes--)
         *val++ = readb(priv->base + offset + i++);

Do you mean that as replacement for "memcpy_fromio" or the whole
function code?
The reason for using __ioread32_copy() was to improve reading
performance (using aligned 32 bit access where possible). I'm not sure
if that really matters?

P.S.
Please don't yell at me in every sentence :( Makes me a bit sad :(

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel