Commit b3e79e76 authored by Serge Semin's avatar Serge Semin Committed by Miquel Raynal
Browse files

mtd: physmap: Add Baikal-T1 physically mapped ROM support 



Baikal-T1 Boot Controller provides an access to a RO storages, which are
physically mapped into the SoC MMIO space. In particularly there are
Internal ROM embedded into the SoC with a pre-installed firmware,
externally attached SPI flash (also accessed in the read-only mode) and a
memory region, which mirrors one of them in accordance with the currently
enabled system boot mode (also called Boot ROM).

This commit adds the Internal ROM support to the physmap driver of the MTD
kernel subsystem. The driver will create the Internal ROM MTD as long as
it is defined in the system dts file. The physically mapped SPI flash
region will be used to implement the SPI-mem interface. The mirroring
memory region won't be accessible directly since it's redundant due to
both bootable regions being exposed anyway.

Note we had to create a dedicated code for the ROMs since read from the
corresponding memory regions must be done via the dword-aligned addresses.

Signed-off-by: default avatarSerge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: linux-mips@vger.kernel.org
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200920111445.21816-1-Sergey.Semin@baikalelectronics.ru
parent 6aec345e

drivers/mtd/maps/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -75,6 +75,17 @@ config MTD_PHYSMAP_OF 
	  physically into the CPU's memory. The mapping description here is

	  taken from OF device tree.



config MTD_PHYSMAP_BT1_ROM

	bool "Baikal-T1 Boot ROMs OF-based physical memory map handling"

	depends on MTD_PHYSMAP_OF

	depends on MIPS_BAIKAL_T1 || COMPILE_TEST

	select MTD_COMPLEX_MAPPINGS

	select MULTIPLEXER

	select MUX_MMIO

	help

	  This provides some extra DT physmap parsing for the Baikal-T1

	  platforms, some detection and setting up ROMs-specific accessors.



config MTD_PHYSMAP_VERSATILE

	bool "ARM Versatile OF-based physical memory map handling"

	depends on MTD_PHYSMAP_OF

drivers/mtd/maps/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ obj-$(CONFIG_MTD_CK804XROM) += ck804xrom.o 
obj-$(CONFIG_MTD_TSUNAMI)	+= tsunami_flash.o

obj-$(CONFIG_MTD_PXA2XX)	+= pxa2xx-flash.o

physmap-objs-y			+= physmap-core.o

physmap-objs-$(CONFIG_MTD_PHYSMAP_BT1_ROM) += physmap-bt1-rom.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

drivers/mtd/maps/physmap-bt1-rom.c

0 → 100644
+126 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC

 *

 * Authors:

 *   Serge Semin <Sergey.Semin@baikalelectronics.ru>

 *

 * Baikal-T1 Physically Mapped Internal ROM driver

 */

#include <linux/bits.h>

#include <linux/device.h>

#include <linux/kernel.h>

#include <linux/mtd/map.h>

#include <linux/mtd/xip.h>

#include <linux/mux/consumer.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/platform_device.h>

#include <linux/string.h>

#include <linux/types.h>



#include "physmap-bt1-rom.h"



/*

 * Baikal-T1 SoC ROMs are only accessible by the dword-aligned instructions.

 * We have to take this into account when implementing the data read-methods.

 * Note there is no need in bothering with endianness, since both Baikal-T1

 * CPU and MMIO are LE.

 */

static map_word __xipram bt1_rom_map_read(struct map_info *map,

					  unsigned long ofs)

{

	void __iomem *src = map->virt + ofs;

	unsigned long shift;

	map_word ret;

	u32 data;



	/* Read data within offset dword. */

	shift = (unsigned long)src & 0x3;

	data = readl_relaxed(src - shift);

	if (!shift) {

		ret.x[0] = data;

		return ret;

	}

	ret.x[0] = data >> (shift * BITS_PER_BYTE);



	/* Read data from the next dword. */

	shift = 4 - shift;

	if (ofs + shift >= map->size)

		return ret;



	data = readl_relaxed(src + shift);

	ret.x[0] |= data << (shift * BITS_PER_BYTE);



	return ret;

}



static void __xipram bt1_rom_map_copy_from(struct map_info *map,

					   void *to, unsigned long from,

					   ssize_t len)

{

	void __iomem *src = map->virt + from;

	ssize_t shift, chunk;

	u32 data;



	if (len <= 0 || from >= map->size)

		return;



	/* Make sure we don't go over the map limit. */

	len = min_t(ssize_t, map->size - from, len);



	/*

	 * Since requested data size can be pretty big we have to implement

	 * the copy procedure as optimal as possible. That's why it's split

	 * up into the next three stages: unaligned head, aligned body,

	 * unaligned tail.

	 */

	shift = (ssize_t)src & 0x3;

	if (shift) {

		chunk = min_t(ssize_t, 4 - shift, len);

		data = readl_relaxed(src - shift);

		memcpy(to, &data + shift, chunk);

		src += chunk;

		to += chunk;

		len -= chunk;

	}



	while (len >= 4) {

		data = readl_relaxed(src);

		memcpy(to, &data, 4);

		src += 4;

		to += 4;

		len -= 4;

	}



	if (len) {

		data = readl_relaxed(src);

		memcpy(to, &data, len);

	}

}



int of_flash_probe_bt1_rom(struct platform_device *pdev,

			   struct device_node *np,

			   struct map_info *map)

{

	struct device *dev = &pdev->dev;



	/* It's supposed to be read-only MTD. */

	if (!of_device_is_compatible(np, "mtd-rom")) {

		dev_info(dev, "No mtd-rom compatible string\n");

		return 0;

	}



	/* Multiplatform guard. */

	if (!of_device_is_compatible(np, "baikal,bt1-int-rom"))

		return 0;



	/* Sanity check the device parameters retrieved from DTB. */

	if (map->bankwidth != 4)

		dev_warn(dev, "Bank width is supposed to be 32 bits wide\n");



	map->read = bt1_rom_map_read;

	map->copy_from = bt1_rom_map_copy_from;



	return 0;

}

drivers/mtd/maps/physmap-bt1-rom.h

0 → 100644
+17 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

#include <linux/mtd/map.h>

#include <linux/of.h>



#ifdef CONFIG_MTD_PHYSMAP_BT1_ROM

int of_flash_probe_bt1_rom(struct platform_device *pdev,

			   struct device_node *np,

			   struct map_info *map);

#else

static inline

int of_flash_probe_bt1_rom(struct platform_device *pdev,

			   struct device_node *np,

			   struct map_info *map)

{

	return 0;

}

#endif

drivers/mtd/maps/physmap-core.c

+5 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/pm_runtime.h>

#include <linux/gpio/consumer.h>



#include "physmap-bt1-rom.h"

#include "physmap-gemini.h"

#include "physmap-ixp4xx.h"

#include "physmap-versatile.h"
@@ -371,6 +372,10 @@ static int physmap_flash_of_init(struct platform_device *dev) 
		info->maps[i].bankwidth = bankwidth;

		info->maps[i].device_node = dp;



		err = of_flash_probe_bt1_rom(dev, dp, &info->maps[i]);

		if (err)

			return err;



		err = of_flash_probe_gemini(dev, dp, &info->maps[i]);

		if (err)

			return err;

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