diff options
Diffstat (limited to 'drivers/mtd/maps/physmap-ixp4xx.c')
-rw-r--r-- | drivers/mtd/maps/physmap-ixp4xx.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/drivers/mtd/maps/physmap-ixp4xx.c b/drivers/mtd/maps/physmap-ixp4xx.c new file mode 100644 index 0000000000..c561468f95 --- /dev/null +++ b/drivers/mtd/maps/physmap-ixp4xx.c @@ -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/platform_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; +} |