csky: Fixup compile error

: error: C++ style comments are not allowed in ISO C90
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
^
error: (this will be reported only once per input file)

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky/mm/highmem: Switch to generic kmap atomic

No reason having the same code in every architecture.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20201103095857.681196473@linutronix.de

csky: Separate fixaddr_init from highmem

After fixaddr_init is separated from highmem, we could use tcm
without highmem selected. (610 (abiv1) don't support highmem,
but it could use tcm now.)

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Tightly-Coupled Memory or Sram support

The implementation are not only used by TCM but also used by sram on
SOC bus. It follow existed linux tcm software interface, so that old
tcm application codes could be re-used directly.

Software interface list in asm/tcm.h:
- Variables/Const: __tcmdata, __tcmconst
- Functions: __tcmfunc, __tcmlocalfunc
- Malloc/Free: tcm_alloc, tcm_free

In linux menuconfig:
- Choose a TCM contain instrctions + data or separated in ITCM/DTCM.
- Determine TCM_BASE (DTCM_BASE) in phyiscal address.
- Determine size of TCM or ITCM(DTCM) in page counts.

Here is hello tcm example from Documentation/arm/tcm.rst which could
be directly used:

/* Uninitialized data */
static u32 __tcmdata tcmvar;
/* Initialized data */
static u32 __tcmdata tcmassigned = 0x2BADBABEU;
/* Constant */
static const u32 __tcmconst tcmconst = 0xCAFEBABEU;

static void __tcmlocalfunc tcm_to_tcm(void)
{
int i;
for (i = 0; i < 100; i++)
tcmvar ++;
}

static void __tcmfunc hello_tcm(void)
{
/* Some abstract code that runs in ITCM */
int i;
for (i = 0; i < 100; i++) {
tcmvar ++;
}
tcm_to_tcm();
}

static void __init test_tcm(void)
{
u32 *tcmem;
int i;

hello_tcm();
printk("Hello TCM executed from ITCM RAM\n");

printk("TCM variable from testrun: %u @ %p\n", tcmvar, &tcmvar);
tcmvar = 0xDEADBEEFU;
printk("TCM variable: 0x%x @ %p\n", tcmvar, &tcmvar);

printk("TCM assigned variable: 0x%x @ %p\n", tcmassigned, &tcmassigned);

printk("TCM constant: 0x%x @ %p\n", tcmconst, &tcmconst);

/* Allocate some TCM memory from the pool */
tcmem = tcm_alloc(20);
if (tcmem) {
printk("TCM Allocated 20 bytes of TCM @ %p\n", tcmem);
tcmem[0] = 0xDEADBEEFU;
tcmem[1] = 0x2BADBABEU;
tcmem[2] = 0xCAFEBABEU;
tcmem[3] = 0xDEADBEEFU;
tcmem[4] = 0x2BADBABEU;
for (i = 0; i < 5; i++)
printk("TCM tcmem[%d] = %08x\n", i, tcmem[i]);
tcm_free(tcmem, 20);
}
}

TODO:
- Separate fixup mapping from highmem
- Support abiv1

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: MMU and page table management

This patch adds files related to memory management and here is our
memory-layout:

Fixmap : 0xffc02000 – 0xfffff000 (4 MB - 12KB)
Pkmap : 0xff800000 – 0xffc00000 (4 MB)
Vmalloc : 0xf0200000 – 0xff000000 (238 MB)
Lowmem : 0x80000000 – 0xc0000000 (1GB)

abiv1 CPU (CK610) is VIPT cache and it doesn't support highmem.
abiv2 CPUs are all PIPT cache and they could support highmem.

Lowmem is directly mapped by msa0 & msa1 reg, and we needn't setup
memory page table for it.

Link:https://lore.kernel.org/lkml/20180518215548.GH17671@n2100.armlinux.org.uk/
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>