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Re: [Qemu-devel] [PATCH v3] sam460ex: Fix sam460ex device tree when boot

From: Guenter Roeck
Subject: Re: [Qemu-devel] [PATCH v3] sam460ex: Fix sam460ex device tree when booting the Linux kernel
Date: Sat, 23 Jun 2018 13:54:40 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0

On 06/23/2018 01:44 PM, BALATON Zoltan wrote:
On Sat, 23 Jun 2018, Guenter Roeck wrote:
sam460ex (or at least this emulation) does not support the "ibm,cpm" power
management. As a result, Linux crashes when trying to access it. Remove
its device tree node. Also, if/when we boot the Linux kernel directly,
serial port clock frequencies in the device tree file will be unset, and
serial port initialization will fail. Add valid frequency values to
the serial ports to be able to use it. Also set valid values for the other
clock nodes otherwise set by u-boot.

Signed-off-by: Guenter Roeck <address@hidden>
v3: Fix style problems (ERROR: braces {} are necessary for all arms ...)
   Use defines flor clock frequencies.
   Use clock frequencies as reported by u-boot in real system.
   Use more specific prefix in subject
   Fi typos in description
v2: Initialize all serial nodes to match u-boot behavior more closely.
   Use direct fdt API functions and ignore errors when clearing out
   /cpm and for setting the serial port clocks.

hw/ppc/sam460ex.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
index bdc53d2..3b90196 100644
--- a/hw/ppc/sam460ex.c
+++ b/hw/ppc/sam460ex.c
@@ -37,6 +37,8 @@
#include "hw/i2c/smbus.h"
#include "hw/usb/hcd-ehci.h"

+#include <libfdt.h>
#define BINARY_DEVICE_TREE_FILE "canyonlands.dtb"
#define UBOOT_FILENAME "u-boot-sam460-20100605.bin"
/* to extract the official U-Boot bin from the updater: */
@@ -67,6 +69,9 @@

#define CPU_FREQ 1150000000
+#define PLB_FREQ 230000000
+#define OPB_FREQ 115000000
+#define EBC_FREQ 115000000
#define SDRAM_NR_BANKS 4

/* FIXME: See u-boot.git 8ac41e, also fix in ppc440_uc.c */
@@ -255,6 +260,7 @@ static int sam460ex_load_device_tree(hwaddr addr,
    void *fdt;
    uint32_t tb_freq = CPU_FREQ;
    uint32_t clock_freq = CPU_FREQ;
+    int offset;

    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, BINARY_DEVICE_TREE_FILE);
    if (!filename) {
@@ -308,6 +314,27 @@ static int sam460ex_load_device_tree(hwaddr addr,
    qemu_fdt_setprop_cell(fdt, "/cpus/address@hidden", "timebase-frequency",

+    /* Remove cpm node if it exists (it is not emulated) */
+    offset = fdt_path_offset(fdt, "/cpm");
+    if (offset >= 0) {
+        fdt_nop_node(fdt, offset);
+    }
+    /* set serial port clocks */
+    offset = fdt_node_offset_by_compatible(fdt, -1, "ns16550");
+    while (offset >= 0) {
+        fdt_setprop_cell(fdt, offset, "clock-frequency", PLB_FREQ);

Not sure if this is relevant, but the include/configs/Sam460ex.h in the 
sam460ex u-boot seems to have:

#define CONFIG_SYS_EXT_SERIAL_CLOCK     11059200 /* use external 11.059MHz clk  

which may be used by u-boot to set uart_clk which is used to set this if I've 
followed it correctly (but maybe I haven't, it's not easy with all the 
#ifdefs). Otherwise:

Yes, you are correct. Sorry, I messed this up - I thought it was PLB_FREQ.
I'll send out v4.


Reviewed-by: BALATON Zoltan <address@hidden>

+        offset = fdt_node_offset_by_compatible(fdt, offset, "ns16550");
+    }
+    /* some more clocks */
+    qemu_fdt_setprop_cell(fdt, "/plb", "clock-frequency",
+                              PLB_FREQ);
+    qemu_fdt_setprop_cell(fdt, "/plb/opb", "clock-frequency",
+                              OPB_FREQ);
+    qemu_fdt_setprop_cell(fdt, "/plb/opb/ebc", "clock-frequency",
+                              EBC_FREQ);
    rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
    ret = fdt_size;

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