[PATCH 1/4] m68k/atari - stram: alloc ST-RAM pool even if kernel not in ST-RAM

Michael Schmitz
2014-03-30T00:01:36Z

With the kernel loaded to FastRAM (TT-RAM), none of the ST-RAM
address range is mapped by init_mem, and ST-RAM is not accessible
through the normal allocation pathways as a result.

Implement ST-RAM pool allocation to be based on physical addresses
always (it already was when the kernel was loaded in ST-RAM).
Return kernel virtual addresses as per normal.

The current test for the kernel residing in ST-RAM always returns
true. Use the bootinfo memory chunk order instead - with the kernel
in FastRAM, ST-RAM (phys. 0x0) is not the first chunk.

In case the kernel is running from FastRAM, delay mapping of ST-RAM
pool until after mem_init.

Provide helper functions for those users of ST-RAM that need
to be aware of the backing physical addresses.

Kudos to Geert for his hints on getting this started.

Signed-off-by: Michael Schmitz <schmitz@debian.org>
---
arch/m68k/atari/stram.c | 75 +++++++++++++++++++++++++++--------
arch/m68k/include/asm/atari_stram.h | 2 +
2 files changed, 60 insertions(+), 17 deletions(-)

diff --git a/arch/m68k/atari/stram.c b/arch/m68k/atari/stram.c
index 0810c8d..afc5d91 100644
--- a/arch/m68k/atari/stram.c
+++ b/arch/m68k/atari/stram.c
@@ -47,6 +47,7 @@ static struct resource stram_pool = {

static unsigned long pool_size = 1024*1024;

+static unsigned long stram_virt_offset;

static int __init atari_stram_setup(char *arg)
{
@@ -67,14 +68,12 @@ early_param("stram_pool", atari_stram_setup);
void __init atari_stram_init(void)
{
int i;
- void *stram_start;

/*
* determine whether kernel code resides in ST-RAM
* (then ST-RAM is the first memory block at virtual 0x0)
*/
- stram_start = phys_to_virt(0);
- kernel_in_stram = (stram_start == 0);
+ kernel_in_stram = (m68k_memory[0].addr == 0);

for (i = 0; i < m68k_num_memory; ++i) {
if (m68k_memory[i].addr == 0) {
@@ -89,24 +88,66 @@ void __init atari_stram_init(void)

/*
* This function is called from setup_arch() to reserve the pages needed for
- * ST-RAM management.
+ * ST-RAM management, if the kernel resides in ST-RAM.
*/
void __init atari_stram_reserve_pages(void *start_mem)
{
- /*
- * always reserve first page of ST-RAM, the first 2 KiB are
- * supervisor-only!
- */
- if (!kernel_in_stram)
- reserve_bootmem(0, PAGE_SIZE, BOOTMEM_DEFAULT);
+ if (kernel_in_stram) {
+ pr_debug("atari_stram pool: kernel in ST-RAM, using alloc_bootmem!\n");
+ stram_pool.start = (resource_size_t)alloc_bootmem_low_pages(pool_size);
+ stram_pool.end = stram_pool.start + pool_size - 1;
+ request_resource(&iomem_resource, &stram_pool);
+ stram_virt_offset = 0;
+ pr_debug("atari_stram pool: size = %lu bytes, resource = %pR\n",
+ pool_size, &stram_pool);
+ pr_debug("atari_stram pool: start = %p, end = %p\n",
+ (void *) stram_pool.start, (void *) stram_pool.end);
+ pr_debug("atari_stram pool: stram_virt_offset = %p\n",
+ (void *) stram_virt_offset);
+ }
+}

- stram_pool.start = (resource_size_t)alloc_bootmem_low_pages(pool_size);
- stram_pool.end = stram_pool.start + pool_size - 1;
- request_resource(&iomem_resource, &stram_pool);

- pr_debug("atari_stram pool: size = %lu bytes, resource = %pR\n",
- pool_size, &stram_pool);
+/*
+ * This function is called as arch initcall to reserve the pages needed for
+ * ST-RAM management, if the kernel does not reside in ST-RAM.
+ */
+int __init atari_stram_map_pages(void)
+{
+ if (!kernel_in_stram) {
+ /*
+ * Skip page 0, as the fhe first 2 KiB are supervisor-only!
+ */
+ pr_debug("atari_stram pool: kernel not in ST-RAM, using ioremap!\n");
+ stram_pool.start = PAGE_SIZE;
+ stram_pool.end = stram_pool.start + pool_size - 1;
+ request_resource(&iomem_resource, &stram_pool);
+ stram_virt_offset = (unsigned long) ioremap(stram_pool.start,
+ resource_size(&stram_pool)) - stram_pool.start;
+ pr_debug("atari_stram pool: size = %lu bytes, resource = %pR\n",
+ pool_size, &stram_pool);
+ pr_debug("atari_stram pool: start = %p, end = %p\n",
+ (void *) stram_pool.start, (void *) stram_pool.end);
+ pr_debug("atari_stram pool: stram_virt_offset = %p\n",
+ (void *) stram_virt_offset);
+ }
+ return 0;
+}
+arch_initcall(atari_stram_map_pages);
+
+
+void *atari_stram_to_virt(unsigned long phys)
+{
+ return (void *)(phys + stram_virt_offset);
+}
+EXPORT_SYMBOL(atari_stram_to_virt);
+
+
+unsigned long atari_stram_to_phys(void *virt)
+{
+ return (unsigned long)(virt - stram_virt_offset);
}
+EXPORT_SYMBOL(atari_stram_to_phys);

void *atari_stram_alloc(unsigned long size, const char *owner)
@@ -134,14 +175,14 @@ void *atari_stram_alloc(unsigned long size, const char *owner)
}

pr_debug("atari_stram_alloc: returning %pR\n", res);
- return (void *)res->start;
+ return atari_stram_to_virt(res->start);
}
EXPORT_SYMBOL(atari_stram_alloc);

void atari_stram_free(void *addr)
{
- unsigned long start = (unsigned long)addr;
+ unsigned long start = atari_stram_to_phys(addr);
struct resource *res;
unsigned long size;

diff --git a/arch/m68k/include/asm/atari_stram.h b/arch/m68k/include/asm/atari_stram.h
index 62e2759..4e771c2 100644
--- a/arch/m68k/include/asm/atari_stram.h
+++ b/arch/m68k/include/asm/atari_stram.h
@@ -8,6 +8,8 @@
/* public interface */
void *atari_stram_alloc(unsigned long size, const char *owner);
void atari_stram_free(void *);
+void *atari_stram_to_virt(unsigned long phys);
+unsigned long atari_stram_to_phys(void *);

/* functions called internally by other parts of the kernel */
void atari_stram_init(void);
--
1.7.0.4