@@ -96,6 +96,17 @@ config MTD_PHYSMAP_GEMINI
platforms, some detection and setting up parallel mode on the
external interface.
+config MTD_PHYSMAP_IXP4XX
+ bool "Intel IXP4xx OF-based physical memory map handling"
+ depends on MTD_PHYSMAP_OF
+ depends on ARM
+ select MTD_COMPLEX_MAPPINGS
+ select MTD_CFI_BE_BYTE_SWAP if CPU_BIG_ENDIAN
+ default ARCH_IXP4XX
+ help
+ This provides some extra DT physmap parsing for the Intel IXP4xx
+ platforms, some elaborate endianness handling in particular.
+
config MTD_PHYSMAP_GPIO_ADDR
bool "GPIO-assisted Flash Chip Support"
depends on MTD_PHYSMAP
@@ -20,6 +20,7 @@ obj-$(CONFIG_MTD_PXA2XX) += pxa2xx-flash.o
physmap-objs-y += physmap-core.o
physmap-objs-$(CONFIG_MTD_PHYSMAP_VERSATILE) += physmap-versatile.o
physmap-objs-$(CONFIG_MTD_PHYSMAP_GEMINI) += physmap-gemini.o
+physmap-objs-$(CONFIG_MTD_PHYSMAP_IXP4XX) += physmap-ixp4xx.o
physmap-objs := $(physmap-objs-y)
obj-$(CONFIG_MTD_PHYSMAP) += physmap.o
obj-$(CONFIG_MTD_PISMO) += pismo.o
@@ -41,6 +41,7 @@
#include <linux/gpio/consumer.h>
#include "physmap-gemini.h"
+#include "physmap-ixp4xx.h"
#include "physmap-versatile.h"
struct physmap_flash_info {
@@ -370,6 +371,10 @@ static int physmap_flash_of_init(struct platform_device *dev)
if (err)
return err;
+ err = of_flash_probe_ixp4xx(dev, dp, &info->maps[i]);
+ if (err)
+ return err;
+
err = of_flash_probe_versatile(dev, dp, &info->maps[i]);
if (err)
return err;
new file mode 100644
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel IXP4xx OF physmap add-on
+ * Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Based on the ixp4xx.c map driver, originally written by:
+ * Intel Corporation
+ * Deepak Saxena <dsaxena@mvista.com>
+ * Copyright (C) 2002 Intel Corporation
+ * Copyright (C) 2003-2004 MontaVista Software, Inc.
+ */
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/xip.h>
+#include "physmap-ixp4xx.h"
+
+/*
+ * Read/write a 16 bit word from flash address 'addr'.
+ *
+ * When the cpu is in little-endian mode it swizzles the address lines
+ * ('address coherency') so we need to undo the swizzling to ensure commands
+ * and the like end up on the correct flash address.
+ *
+ * To further complicate matters, due to the way the expansion bus controller
+ * handles 32 bit reads, the byte stream ABCD is stored on the flash as:
+ * D15 D0
+ * +---+---+
+ * | A | B | 0
+ * +---+---+
+ * | C | D | 2
+ * +---+---+
+ * This means that on LE systems each 16 bit word must be swapped. Note that
+ * this requires CONFIG_MTD_CFI_BE_BYTE_SWAP to be enabled to 'unswap' the CFI
+ * data and other flash commands which are always in D7-D0.
+ */
+#ifndef CONFIG_CPU_BIG_ENDIAN
+
+static inline u16 flash_read16(void __iomem *addr)
+{
+ return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
+}
+
+static inline void flash_write16(u16 d, void __iomem *addr)
+{
+ __raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
+}
+
+#define BYTE0(h) ((h) & 0xFF)
+#define BYTE1(h) (((h) >> 8) & 0xFF)
+
+#else
+
+static inline u16 flash_read16(const void __iomem *addr)
+{
+ return __raw_readw(addr);
+}
+
+static inline void flash_write16(u16 d, void __iomem *addr)
+{
+ __raw_writew(d, addr);
+}
+
+#define BYTE0(h) (((h) >> 8) & 0xFF)
+#define BYTE1(h) ((h) & 0xFF)
+#endif
+
+static map_word ixp4xx_read16(struct map_info *map, unsigned long ofs)
+{
+ map_word val;
+
+ val.x[0] = flash_read16(map->virt + ofs);
+ return val;
+}
+
+/*
+ * The IXP4xx expansion bus only allows 16-bit wide acceses
+ * when attached to a 16-bit wide device (such as the 28F128J3A),
+ * so we can't just memcpy_fromio().
+ */
+static void ixp4xx_copy_from(struct map_info *map, void *to,
+ unsigned long from, ssize_t len)
+{
+ u8 *dest = (u8 *) to;
+ void __iomem *src = map->virt + from;
+
+ if (len <= 0)
+ return;
+
+ if (from & 1) {
+ *dest++ = BYTE1(flash_read16(src-1));
+ src++;
+ --len;
+ }
+
+ while (len >= 2) {
+ u16 data = flash_read16(src);
+ *dest++ = BYTE0(data);
+ *dest++ = BYTE1(data);
+ src += 2;
+ len -= 2;
+ }
+
+ if (len > 0)
+ *dest++ = BYTE0(flash_read16(src));
+}
+
+static void ixp4xx_write16(struct map_info *map, map_word d, unsigned long adr)
+{
+ flash_write16(d.x[0], map->virt + adr);
+}
+
+int of_flash_probe_ixp4xx(struct platform_device *pdev,
+ struct device_node *np,
+ struct map_info *map)
+{
+ struct device *dev = &pdev->dev;
+
+ /* Multiplatform guard */
+ if (!of_device_is_compatible(np, "intel,ixp4xx-flash"))
+ return 0;
+
+ map->read = ixp4xx_read16;
+ map->write = ixp4xx_write16;
+ map->copy_from = ixp4xx_copy_from;
+ map->copy_to = NULL;
+
+ dev_info(dev, "initialized Intel IXP4xx-specific physmap control\n");
+
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/of.h>
+#include <linux/mtd/map.h>
+
+#ifdef CONFIG_MTD_PHYSMAP_IXP4XX
+int of_flash_probe_ixp4xx(struct platform_device *pdev,
+ struct device_node *np,
+ struct map_info *map);
+#else
+static inline
+int of_flash_probe_ixp4xx(struct platform_device *pdev,
+ struct device_node *np,
+ struct map_info *map)
+{
+ return 0;
+}
+#endif
In order to support device tree probing of IXP4xx NOR flash chips, a certain big-endian or mixed-endian memory access pattern need to be used. I have opted to use the pattern set by previous plug-ins to physmap for Gemini and Versatile, just override some functions and reuse most of the physmap core code as it is to minimize maintenance. Parts of drivers/mtd/ixp4xx.c are copied into this file. After we have IXP4xx converted fully to device tree, the drivers/mtd/ixp4xx.c file will be deleted and this will be the only access pattern to the IXP4xx flash. I did not keep the quirk in the flash write function after probe, where the old code for a while checks for access to odd addresses, fails and assigns a "faster" write function once it has convinced probe to only use 2-byte accesses. As we mandate that this device should be using bank-width = <2> this should not be a problem unless misconfigured. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog v3->v4: - Rebase on v5.4-rc1 - Resend ChangeLog v2->v3: - Restrict option to ARM machines as LE on X86 does not feel very good about this code. ChangeLog v1->v2: - Simply select MTD_CFI_BE_BYTE_SWAP on big endian in Kconfig - Rebase on v5.1-rc1 --- drivers/mtd/maps/Kconfig | 11 +++ drivers/mtd/maps/Makefile | 1 + drivers/mtd/maps/physmap-core.c | 5 ++ drivers/mtd/maps/physmap-ixp4xx.c | 132 ++++++++++++++++++++++++++++++ drivers/mtd/maps/physmap-ixp4xx.h | 17 ++++ 5 files changed, 166 insertions(+) create mode 100644 drivers/mtd/maps/physmap-ixp4xx.c create mode 100644 drivers/mtd/maps/physmap-ixp4xx.h -- 2.21.0 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/