On Mon, Oct 08, 2012 at 02:59:19PM +0100, Jon Medhurst (Tixy) wrote:
From: Jon Medhurst tixy@linaro.org
The A15xA7 models simulate a Cache Coherent Interconnect (CCI) and this needs to be initialised correctly for Linux to boot.
To perform this initiation we add the new function configure_from_fdt() which will look in the fdt for devices to initialise. In this first case we look for the CCI node and if found then setup this device.
Acked-by: Dave Martin dave.martin@linaro.org
(Commentary below, but the patch looks OK to me.)
Signed-off-by: Jon Medhurst tixy@linaro.org
semi_loader.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+)
diff --git a/semi_loader.c b/semi_loader.c index c9750be..b0c064c 100644 --- a/semi_loader.c +++ b/semi_loader.c @@ -242,6 +242,61 @@ libfdt_error: fatal("libfdt: ", fdt_strerror(e), ", while updating device tree\n"); } +/* For accessing 32-bit device ports */ +#define io32(p) (*(volatile uint32_t *)(p))
I had a vague memory of something like this already existing somewhere, but I think I may be confusing this with another codebase.
+static void init_cci(unsigned cci) +{
- info("Initialising CCI\n");
- /*
* Ideally, the CCI device tree binding would include suitable* information so we can correctly configure the CCI, but for* now we'll just hard-code settings for the present A15xA7* models.*/- /* Turn on CCI snoops and DVM messages */
- io32(cci+0x4000) = 0x3; /* A15 cluster */
- io32(cci+0x5000) = 0x3; /* A7 cluster */
We may want to be more sophisticated about this at some point, but this is a sensible compromise for now.
There is no official CCI binding yet, but this code makes reasonable- looking, minimal assumptions about its final form.
- /* Wait while change pending bit of status register is set */
- while(io32(cci+0xc) & 0x1)
{}+}
+static void configure_from_fdt(struct loader_info *info) +{
- void *fdt = (void *)info->fdt_start;
- uint32_t const *p;
- int addrcells, sizecells;
- int offset, len;
- if(!fdt)
return;- _fdt_address_and_size_cells(fdt, &addrcells, &sizecells);
- /* See if there is a CCI device to initialise */
- offset = fdt_node_offset_by_compatible(fdt, 0, "arm,cci");
- if (offset >= 0) {
p = fdt_getprop(fdt, offset, "reg", &len);if(len != (addrcells + sizecells) * 4)info("Failed parsing device-tree node for CCI\n");else {/** p[addrcells - 1] is the least significant 32-bits of* the address for the CCI. On 32-bit CPUs any additional* address bits had better be zero otherwise we can't* access it as we don't enable the MMU.*/init_cci(fdt32_to_cpu(p[addrcells - 1]));}- }
- return;
+}
static int is_space(char c) { return c == ' '; @@ -598,4 +653,6 @@ args_done: atag_append(&atagp, ATAG_NONE, 0, 0); update_fdt(&phys, info);
- configure_from_fdt(info);
}
1.7.10.4