[PATCH v2 1/6] powerpc: Add hardware description string

[Michael Ellerman <mpe@ellerman.id.au>]

Create a hardware description string, which we will use to record
various details of the hardware platform we are running on.

Print the accumulated description at boot, and use it to set the generic
description which is printed in oopses.

To begin with add ppc_md.name, aka the "machine description".

Example output at boot with the full series applied:

  Linux version 6.0.0-rc2-gcc-11.1.0-00199-g893f9007a5ce-dirty (michael@alpine1-p1) (powerpc64-linux-gcc (GCC) 11.1.0, GNU ld (GNU Binutils) 2.36.1) #844 SMP Thu Sep 29 22:29:53 AEST 2022
  Hardware name: model:'IBM pSeries (emulated by qemu)' cpu:'POWER8 (raw)' pvr:0x4d0200 lpvr:0xf000004 of:'SLOF,HEAD' machine:pSeries
  printk: bootconsole [udbg0] enabled

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/include/asm/setup.h   |  2 ++
 arch/powerpc/kernel/setup-common.c | 19 ++++++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

v2: Print the string at boot as suggested by Nathan.
    Add some comments, update change log.

diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index dd98f43bd685..99f1c52a3ca4 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -588,6 +590,15 @@ static __init int add_pcspkr(void)
 device_initcall(add_pcspkr);
 #endif	/* CONFIG_PCSPKR_PLATFORM */
 
+static char ppc_hw_desc_buf[128] __initdata;
+
+struct seq_buf ppc_hw_desc __initdata = {
+	.buffer = ppc_hw_desc_buf,
+	.size = sizeof(ppc_hw_desc_buf),
+	.len = 0,
+	.readpos = 0,
+};
+
 static __init void probe_machine(void)
 {
 	extern struct machdep_calls __machine_desc_start;
@@ -628,7 +639,13 @@ static __init void probe_machine(void)
 		for (;;);
 	}
 
-	printk(KERN_INFO "Using %s machine description\n", ppc_md.name);
+	// Append the machine name to other info we've gathered
+	seq_buf_printf(&ppc_hw_desc, "machine:%s", ppc_md.name);
+
+	// Set the generic hardware description shown in oopses
+	dump_stack_set_arch_desc(ppc_hw_desc.buffer);
+
+	pr_info("Hardware name: %s\n", ppc_hw_desc.buffer);
 }
 
 /* Match a class of boards, not a specific device configuration. */
-- 
2.37.3