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
--- /dev/null
+// 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;
+}
projects / mirror_ubuntu-hirsute-kernel.git / commitdiff