From: Jon Medhurst <tixy@xxxxxxxxxx>
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.
Signed-off-by: Jon Medhurst <tixy@xxxxxxxxxx>
---
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))
+
+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 */
+
+ /* 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
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
