RISC-V: Add mvendorid, marchid, and mimpid to /proc/cpuinfo output

I'm merging this in as a single commit as it's a dependency for some
other work.

* commit '3baca1a4d490484fcd555413f1fec85b2e071912':
  RISC-V: Add mvendorid, marchid, and mimpid to /proc/cpuinfo output

diff --combined arch/riscv/kernel/cpu.c
index 87455d12970f3c704c0176d4b521071d2234f563,250220e2ccebf38d5a77535dbc58c30ac0bbb2d9..0937595c32a5348ecb08316fc04e1cd97d9761d3
--- 1/arch/riscv/kernel/cpu.c
--- 2/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@@ -3,10 -3,13 +3,13 @@@
   * Copyright (C) 2012 Regents of the University of California
   */
  
+ #include <linux/cpu.h>
  #include <linux/init.h>
  #include <linux/seq_file.h>
  #include <linux/of.h>
+ #include <asm/csr.h>
  #include <asm/hwcap.h>
+ #include <asm/sbi.h>
  #include <asm/smp.h>
  #include <asm/pgtable.h>
  
@@@ -68,6 -71,50 +71,50 @@@ int riscv_of_parent_hartid(struct devic
  }
  
  #ifdef CONFIG_PROC_FS
+ 
+ struct riscv_cpuinfo {
+       unsigned long mvendorid;
+       unsigned long marchid;
+       unsigned long mimpid;
+ };
+ static DEFINE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
+ 
+ static int riscv_cpuinfo_starting(unsigned int cpu)
+ {
+       struct riscv_cpuinfo *ci = this_cpu_ptr(&riscv_cpuinfo);
+ 
+ #if IS_ENABLED(CONFIG_RISCV_SBI)
+       ci->mvendorid = sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
+       ci->marchid = sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
+       ci->mimpid = sbi_spec_is_0_1() ? 0 : sbi_get_mimpid();
+ #elif IS_ENABLED(CONFIG_RISCV_M_MODE)
+       ci->mvendorid = csr_read(CSR_MVENDORID);
+       ci->marchid = csr_read(CSR_MARCHID);
+       ci->mimpid = csr_read(CSR_MIMPID);
+ #else
+       ci->mvendorid = 0;
+       ci->marchid = 0;
+       ci->mimpid = 0;
+ #endif
+ 
+       return 0;
+ }
+ 
+ static int __init riscv_cpuinfo_init(void)
+ {
+       int ret;
+ 
+       ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/cpuinfo:starting",
+                               riscv_cpuinfo_starting, NULL);
+       if (ret < 0) {
+               pr_err("cpuinfo: failed to register hotplug callbacks.\n");
+               return ret;
+       }
+ 
+       return 0;
+ }
+ device_initcall(riscv_cpuinfo_init);
+ 
  #define __RISCV_ISA_EXT_DATA(UPROP, EXTID) \
        {                                                       \
                .uprop = #UPROP,                                \
@@@ -92,10 -139,10 +139,10 @@@
   */
  static struct riscv_isa_ext_data isa_ext_arr[] = {
        __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 +      __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
        __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
        __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
        __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 -      __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
        __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
  };
  
@@@ -185,6 -232,7 +232,7 @@@ static int c_show(struct seq_file *m, v
  {
        unsigned long cpu_id = (unsigned long)v - 1;
        struct device_node *node = of_get_cpu_node(cpu_id, NULL);
+       struct riscv_cpuinfo *ci = per_cpu_ptr(&riscv_cpuinfo, cpu_id);
        const char *compat, *isa;
  
        seq_printf(m, "processor\t: %lu\n", cpu_id);
@@@ -195,6 -243,9 +243,9 @@@
        if (!of_property_read_string(node, "compatible", &compat)
            && strcmp(compat, "riscv"))
                seq_printf(m, "uarch\t\t: %s\n", compat);
+       seq_printf(m, "mvendorid\t: 0x%lx\n", ci->mvendorid);
+       seq_printf(m, "marchid\t\t: 0x%lx\n", ci->marchid);
+       seq_printf(m, "mimpid\t\t: 0x%lx\n", ci->mimpid);
        seq_puts(m, "\n");
        of_node_put(node);