ACPI / CPPC: Add support for functional fixed hardware address

The CPPC registers can also be accessed via functional fixed hardware
addresse(FFH) in X86. Add support by modifying cpc_read and cpc_write to
be able to read/write MSRs on x86 platform on per cpu basis.
Also with this change, acpi_cppc_processor_probe doesn't bail out if
address space id is not equal to PCC or memory address space and FFH
is supported on the system.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/x86/kernel/acpi/Makefile

 obj-$(CONFIG_ACPI)		+= boot.o
 obj-$(CONFIG_ACPI_SLEEP)	+= sleep.o wakeup_$(BITS).o
 obj-$(CONFIG_ACPI_APEI)		+= apei.o
+obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_msr.o
 
 ifneq ($(CONFIG_ACPI_PROCESSOR),)
 obj-y				+= cstate.o

arch/x86/kernel/acpi/cppc_msr.c

+/*
+ * cppc_msr.c:  MSR Interface for CPPC
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <acpi/cppc_acpi.h>
+#include <asm/msr.h>
+
+/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
+
+bool cpc_ffh_supported(void)
+{
+	return true;
+}
+
+int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
+{
+	int err;
+
+	err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
+	if (!err) {
+		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
+				       reg->bit_offset);
+
+		*val &= mask;
+		*val >>= reg->bit_offset;
+	}
+	return err;
+}
+
+int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
+{
+	u64 rd_val;
+	int err;
+
+	err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
+	if (!err) {
+		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
+				       reg->bit_offset);
+
+		val <<= reg->bit_offset;
+		val &= mask;
+		rd_val &= ~mask;
+		rd_val |= val;
+		err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
+	}
+	return err;
+}

drivers/acpi/cppc_acpi.c

@@ -579,6 +579,19 @@ static int register_pcc_channel(int pcc_subspace_idx)
 	return 0;
 }
 
+/**
+ * cpc_ffh_supported() - check if FFH reading supported
+ *
+ * Check if the architecture has support for functional fixed hardware
+ * read/write capability.
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_ffh_supported(void)
+{
+	return false;
+}
+
 /*
  * An example CPC table looks like the following.
  *
@@ -728,9 +741,11 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 					cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
 				}
 			} else {
-				/* Support only PCC and SYS MEM type regs */
-				pr_debug("Unsupported register type: %d\n", gas_t->space_id);
-				goto out_free;
+				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
+					/* Support only PCC ,SYS MEM and FFH type regs */
+					pr_debug("Unsupported register type: %d\n", gas_t->space_id);
+					goto out_free;
+				}
 			}
 
 			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
@@ -819,13 +834,43 @@ void acpi_cppc_processor_exit(struct acpi_processor *pr)
 }
 EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
 
+/**
+ * cpc_read_ffh() - Read FFH register
+ * @cpunum:	cpu number to read
+ * @reg:	cppc register information
+ * @val:	place holder for return value
+ *
+ * Read bit_width bits from a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
+{
+	return -ENOTSUPP;
+}
+
+/**
+ * cpc_write_ffh() - Write FFH register
+ * @cpunum:	cpu number to write
+ * @reg:	cppc register information
+ * @val:	value to write
+ *
+ * Write value of bit_width bits to a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
+{
+	return -ENOTSUPP;
+}
+
 /*
  * Since cpc_read and cpc_write are called while holding pcc_lock, it should be
  * as fast as possible. We have already mapped the PCC subspace during init, so
  * we can directly write to it.
  */
 
-static int cpc_read(struct cpc_register_resource *reg_res, u64 *val)
+static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 {
 	int ret_val = 0;
 	void __iomem *vaddr = 0;
@@ -841,6 +886,8 @@ static int cpc_read(struct cpc_register_resource *reg_res, u64 *val)
 		vaddr = GET_PCC_VADDR(reg->address);
 	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		vaddr = reg_res->sys_mem_vaddr;
+	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+		return cpc_read_ffh(cpu, reg, val);
 	else
 		return acpi_os_read_memory((acpi_physical_address)reg->address,
 				val, reg->bit_width);
@@ -867,7 +914,7 @@ static int cpc_read(struct cpc_register_resource *reg_res, u64 *val)
 	return ret_val;
 }
 
-static int cpc_write(struct cpc_register_resource *reg_res, u64 val)
+static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 {
 	int ret_val = 0;
 	void __iomem *vaddr = 0;
@@ -877,6 +924,8 @@ static int cpc_write(struct cpc_register_resource *reg_res, u64 val)
 		vaddr = GET_PCC_VADDR(reg->address);
 	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		vaddr = reg_res->sys_mem_vaddr;
+	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+		return cpc_write_ffh(cpu, reg, val);
 	else
 		return acpi_os_write_memory((acpi_physical_address)reg->address,
 				val, reg->bit_width);
@@ -941,13 +990,13 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
 		}
 	}
 
-	cpc_read(highest_reg, &high);
+	cpc_read(cpunum, highest_reg, &high);
 	perf_caps->highest_perf = high;
 
-	cpc_read(lowest_reg, &low);
+	cpc_read(cpunum, lowest_reg, &low);
 	perf_caps->lowest_perf = low;
 
-	cpc_read(nom_perf, &nom);
+	cpc_read(cpunum, nom_perf, &nom);
 	perf_caps->nominal_perf = nom;
 
 	if (!high || !low || !nom)
@@ -1004,9 +1053,9 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
 		}
 	}
 
-	cpc_read(delivered_reg, &delivered);
-	cpc_read(reference_reg, &reference);
-	cpc_read(ref_perf_reg, &ref_perf);
+	cpc_read(cpunum, delivered_reg, &delivered);
+	cpc_read(cpunum, reference_reg, &reference);
+	cpc_read(cpunum, ref_perf_reg, &ref_perf);
 
 	/*
 	 * Per spec, if ctr_wrap_time optional register is unsupported, then the
@@ -1015,7 +1064,7 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
 	 */
 	ctr_wrap_time = (u64)(~((u64)0));
 	if (CPC_SUPPORTED(ctr_wrap_reg))
-		cpc_read(ctr_wrap_reg, &ctr_wrap_time);
+		cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
 
 	if (!delivered || !reference ||	!ref_perf) {
 		ret = -EFAULT;
@@ -1082,7 +1131,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * Skip writing MIN/MAX until Linux knows how to come up with
 	 * useful values.
 	 */
-	cpc_write(desired_reg, perf_ctrls->desired_perf);
+	cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
 
 	if (CPC_IN_PCC(desired_reg))
 		up_read(&pcc_data.pcc_lock);	/* END Phase-I */