[U-Boot] [PATCH v2 11/12] arm: add MMU/d-cache support for Faraday cores

Albert ARIBAUD
2013-04-18T19:09:58Z

Hi Kuo-Jung,

On Thu, 18 Apr 2013 17:25:38 +0800, Kuo-Jung Su <dantesu@gmail.com>
wrote:

> From: Kuo-Jung Su <dantesu@faraday-tech.com>
>
> This patch would enable MMU for Faraday ARMv5TE cores.
>
> Here is the abstract of this MMU design.
>
> Assume SDRAM memory region starts at 0x10000000, and its size = 0x800000.
>
> 0x00000000 +-------------------+
> | |
> | UN-CACHED |
> | |
> | |
> 0x10000000 +-------------------+
> | CACHED (SDRAM) | <- It's where data/bss/stack lived.
> | |
> | |
> 0x10800000 +-------------------+
> | |
> | |
> | UN-CACHED |
> | |
> | |
> 0xFF800000 +-------------------+
> | UN-CACHED (SDRAM) | <- An un-cached shadow of the SDRAM.
> | | dma_alloc_coherent() always returns
> | | an address in this region.
> 0xFFFFFFFF +-------------------+

The ASCII map is great for explaining, but I find it a bit big for a
commit message. Can you summarize it as lines like

0x00000000-0x0FFFFFFF not cached
0x10000000-0x107FFFFF cached (SDRAM)
...

?

> Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
> CC: Albert Aribaud <albert.u.boot@aribaud.net>
> ---
> arch/arm/include/asm/dma-mapping.h | 56 ++++++++++++++++++++++--
> arch/arm/include/asm/global_data.h | 4 ++
> arch/arm/include/asm/io.h | 84 +++++++++++++++++++++++++++++++++++-
> arch/arm/lib/cache-cp15.c | 42 ++++++++++++++++++
> common/cmd_boot.c | 4 ++
> 5 files changed, 186 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
> index 5bbb0a0..53c4edf 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -3,6 +3,9 @@
> * Stelian Pop <stelian@popies.net>
> * Lead Tech Design <www.leadtechdesign.com>
> *
> + * (C) Copyright 2010
> + * Dante Su <dantesu@faraday-tech.com>
> + *
> * See file CREDITS for list of people who contributed to this
> * project.
> *
> @@ -24,22 +27,69 @@
> #ifndef __ASM_ARM_DMA_MAPPING_H
> #define __ASM_ARM_DMA_MAPPING_H
>
> +#include <asm/u-boot.h>
> +#include <asm/global_data.h>
> +#include <asm/io.h>
> +#include <malloc.h>
> +
> enum dma_data_direction {
> DMA_BIDIRECTIONAL = 0,
> DMA_TO_DEVICE = 1,
> DMA_FROM_DEVICE = 2,
> };
>
> -static void *dma_alloc_coherent(size_t len, unsigned long *handle)
> +static inline void *dma_alloc_coherent(size_t len, unsigned long *handle)
> +{
> +#if defined(CONFIG_FARADAY) && !defined(CONFIG_SYS_DCACHE_OFF)
> + DECLARE_GLOBAL_DATA_PTR;

I'd rather have the global data ptr be declared outside any function,
and only once.

> +#endif
> + void *va = memalign(ARCH_DMA_MINALIGN, len);
> +
> + if (va && handle)
> + *handle = virt_to_phys(va);
> +
> +#if defined(CONFIG_FARADAY) && !defined(CONFIG_SYS_DCACHE_OFF)
> + if (gd->arch.cpu_mmu) {
> + /* invalidate the buffer, convert to un-cached address */
> + if (va != NULL) {
> + invalidate_dcache_range((ulong)va, (ulong)va + len);
> + va = virt_to_uncached(va);
> + }
> + }
> +#endif
> +
> + return va;
> +}
> +
> +static inline void dma_free_coherent(void *va)
> {
> - *handle = (unsigned long)malloc(len);
> - return (void *)*handle;
> + free(virt_to_cached(va));
> }

If I read this correctly, this code changes the semantics of
dma_alloc_coherent() for boards other than Faraday-based: before,
mempry was simply malloc()ed, now it would be memalign()ed then
virt_to_phys()ed. Why not simply keep the previous implementation under
a #else...#endif block?

> static inline unsigned long dma_map_single(volatile void *vaddr, size_t len,
> enum dma_data_direction dir)
> {
> +#if defined(CONFIG_FARADAY) && !defined(CONFIG_SYS_DCACHE_OFF)
> + DECLARE_GLOBAL_DATA_PTR;
> +
> + if (gd->arch.cpu_mmu) {
> + switch (dir) {
> + case DMA_BIDIRECTIONAL:
> + case DMA_TO_DEVICE:
> + flush_dcache_range((ulong)vaddr,
> + (ulong)vaddr + len);
> + break;
> +
> + case DMA_FROM_DEVICE:
> + invalidate_dcache_range((ulong)vaddr,
> + (ulong)vaddr + len);
> + break;
> + }
> + }
> + return virt_to_phys((void *)vaddr);
> +#else
> return (unsigned long)vaddr;
> +#endif
> }

Here we have such a #else/#endif, which makes sure non-Farady boards
are unaffected.

> static inline void dma_unmap_single(volatile void *vaddr, size_t len,
> diff --git a/arch/arm/include/asm/global_data.h b/arch/arm/include/asm/global_data.h
> index 37ac0da..bd18ff7 100644
> --- a/arch/arm/include/asm/global_data.h
> +++ b/arch/arm/include/asm/global_data.h
> @@ -38,6 +38,10 @@ struct arch_global_data {
> unsigned long pllb_rate_hz;
> unsigned long at91_pllb_usb_init;
> #endif
> +#ifdef CONFIG_FARADAY
> + unsigned long cpu_id;
> + unsigned long cpu_mmu; /* has mmu */
> +#endif
> /* "static data" needed by most of timer.c on ARM platforms */
> unsigned long timer_rate_hz;
> unsigned long tbu;
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index 1fbc531..17d8898 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -2,6 +2,7 @@
> * linux/include/asm-arm/io.h
> *
> * Copyright (C) 1996-2000 Russell King
> + * Copyright (C) 2009-2010 Dante Su <dantesu@faraday-tech.com>
> *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> @@ -23,6 +24,8 @@
> #ifdef __KERNEL__
>
> #include <linux/types.h>
> +#include <asm/u-boot.h>
> +#include <asm/global_data.h>
> #include <asm/byteorder.h>
> #include <asm/memory.h>
> #if 0 /* XXX###XXX */
> @@ -57,9 +60,88 @@ static inline void unmap_physmem(void *vaddr, unsigned long flags)
>
> }
>
> +#ifdef CONFIG_FARADAY
> +
> +# ifndef CONFIG_SYS_DCACHE_OFF
> +
> +static inline ulong uncached_base(volatile gd_t *gd)
> +{
> + return (4096 - (gd->ram_size >> 20)) << 20;

Symbolic constants or a comment would not hurt here.

> +}
> +# endif
> +
> +static inline void *virt_to_cached(void *va)
> +{
> +# ifndef CONFIG_SYS_DCACHE_OFF
> + DECLARE_GLOBAL_DATA_PTR;
> + ulong base = uncached_base(gd);
> +
> + if (!gd->arch.cpu_mmu)
> + return va;
> +
> + if ((ulong)va >= base &&
> + (ulong)va < (base + gd->ram_size))
> + va = (void *)((ulong)va - base + CONFIG_SYS_SDRAM_BASE);
> +# endif /* !CONFIG_SYS_DCACHE_OFF */
> +
> + return va;
> +}
> +
> +static inline void *virt_to_uncached(void *va)
> +{
> +# ifndef CONFIG_SYS_DCACHE_OFF
> + DECLARE_GLOBAL_DATA_PTR;
> + ulong base = uncached_base(gd);
> +
> + if (!gd->arch.cpu_mmu)
> + return va;
> +
> +# ifdef CONFIG_USE_IRQ
> + if ((ulong)va < SZ_1M)
> + return (void *)(base + (ulong)va);
> +# endif
> +
> + if ((ulong)va >= CONFIG_SYS_SDRAM_BASE &&
> + (ulong)va < (CONFIG_SYS_SDRAM_BASE + gd->ram_size))
> + va = (void *)(base + ((ulong)va - CONFIG_SYS_SDRAM_BASE));
> +# endif /* !CONFIG_SYS_DCACHE_OFF */
> +
> + return va;
> +}
> +
> +#endif /* CONFIG_FARADAY */
> +
> static inline phys_addr_t virt_to_phys(void * vaddr)
> {
> - return (phys_addr_t)(vaddr);
> +#if defined(CONFIG_FARADAY) && !defined(CONFIG_SYS_DCACHE_OFF)
> +
> + DECLARE_GLOBAL_DATA_PTR;
> + bd_t *bd = gd->bd;
> + ulong base = uncached_base(gd);
> + ulong phys = (ulong)vaddr;
> +
> + if (!gd->arch.cpu_mmu)
> + return (phys_addr_t)phys;
> +
> + if (phys >= base) {
> + ulong bank;
> + ulong off = phys - base;
> + for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; ++bank) {
> + if (bd->bi_dram[bank].size > off)
> + break;
> + off -= bd->bi_dram[bank].size;
> + }
> + phys = bd->bi_dram[bank].start + off;
> + }
> +# ifdef CONFIG_USE_IRQ
> + else if (phys < SZ_1M && bd->bi_dram[0].start != 0)
> + phys = bd->bi_dram[0].start + phys;
> +# endif
> +
> + return (phys_addr_t)phys;
> +#else
> + return (phys_addr_t)vaddr;
> +#endif
> }
>
> /*
> diff --git a/arch/arm/lib/cache-cp15.c b/arch/arm/lib/cache-cp15.c
> index 4abe1cf..eee8585 100644
> --- a/arch/arm/lib/cache-cp15.c
> +++ b/arch/arm/lib/cache-cp15.c
> @@ -1,6 +1,8 @@
> /*
> * (C) Copyright 2002
> * Wolfgang Denk, DENX Software Engineering, wd at denx.de.
> + * (C) Copyright 2010
> + * Dante Su <dantesu@faraday-tech.com>
> *
> * See file CREDITS for list of people who contributed to this
> * project.
> @@ -87,6 +89,10 @@ __weak void dram_bank_mmu_setup(int bank)
> {
> bd_t *bd = gd->bd;
> int i;
> +#ifdef CONFIG_FARADAY
> + ulong ubase, off;
> + u32 *page_table = (u32 *)gd->arch.tlb_addr;
> +#endif
>
> debug("%s: bank: %d\n", __func__, bank);
> for (i = bd->bi_dram[bank].start >> 20;
> @@ -98,6 +104,32 @@ __weak void dram_bank_mmu_setup(int bank)
> set_section_dcache(i, DCACHE_WRITEBACK);
> #endif
> }
> +#ifdef CONFIG_FARADAY
> +# ifdef CONFIG_USE_IRQ
> + /* map the exception table to 0x00000000 if necessary */
> + if (bank == 0 && bd->bi_dram[bank].start != 0) {
> + u32 pa = bd->bi_dram[bank].start;
> +#if defined(CONFIG_SYS_ARM_CACHE_WRITETHROUGH)
> + page_table[0] = pa | (3 << 10) | DCACHE_WRITETHROUGH;
> +#else
> + page_table[0] = pa | (3 << 10) | DCACHE_WRITEBACK;
> +#endif
> + }
> +# endif
> + /* calculate address offset */
> + off = 0;
> + for (i = 0; i < bank; ++i)
> + off += bd->bi_dram[bank].size;
> +
> + /* create memory map */
> + ubase = (4096 - (gd->ram_size >> 20)) << 20;
> + for (i = 0; i < bd->bi_dram[bank].size >> 20; ++i) {
> + u32 pa = bd->bi_dram[bank].start + (i << 20);
> + /* create un-cached address map */
> + u32 va = ubase + off + (i << 20);
> + page_table[va >> 20] = pa | (3 << 10) | DCACHE_OFF;
> + }
> +#endif
> }
>
> /* to activate the MMU we need to set up virtual memory: use 1M areas */
> @@ -126,6 +158,10 @@ static inline void mmu_setup(void)
>
> /* and enable the mmu */
> reg = get_cr(); /* get control reg. */
> +#ifdef CONFIG_FARADAY
> + reg |= CR_W; /* enable write buffer */
> + reg |= CR_Z; /* enable branch prediction */
> +#endif
> cp_delay();
> set_cr(reg | CR_M);
> }
> @@ -140,9 +176,15 @@ static void cache_enable(uint32_t cache_bit)
> {
> uint32_t reg;
>
> +#ifdef CONFIG_FARADAY
> + if (!gd->arch.cpu_mmu && (cache_bit == CR_C))
> + return;
> +#endif
> +
> /* The data cache is not active unless the mmu is enabled too */
> if ((cache_bit == CR_C) && !mmu_enabled())
> mmu_setup();
> +
> reg = get_cr(); /* get control reg. */
> cp_delay();
> set_cr(reg | cache_bit);
> diff --git a/common/cmd_boot.c b/common/cmd_boot.c
> index d3836fd..b2477e8 100644
> --- a/common/cmd_boot.c
> +++ b/common/cmd_boot.c
> @@ -50,6 +50,10 @@ static int do_go(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>
> printf ("## Starting application at 0x%08lX ...\n", addr);
>
> +#if defined(__ARM__) && !defined(CONFIG_SYS_DCACHE_OFF)
> + cleanup_before_linux();
> +#endif
> +
> /*
> * pass address parameter as argv[0] (aka command name),
> * and all remaining args
> --
> 1.7.9.5
>

Amicalement,
--
Albert.