[PATCH -v2 3/4] ACPI APEI: Convert atomicio routines

[Myron Stowe <myron.stowe@redhat.com>]

From: Myron Stowe <mstowe@redhat.com>

APEI needs memory access in interrupt context.  The obvious choice is
acpi_read(), but originally it couldn't be used in interrupt context
because it makes temporary mappings with ioremap().  Therefore, we added
drivers/acpi/atomicio.c, which provides:
    acpi_pre_map_gar()     -- ioremap in process context
	acpi_atomic_read()     -- memory access in interrupt context
	acpi_post_unmap_gar()  -- iounmap

Later we added acpi_os_map_generic_address() (2971852) and enhanced
acpi_read() so it works in interrupt context as long as the address has
been previously mapped (620242a).  Now this sequence:
    acpi_os_map_generic_address()    -- ioremap in process context
    acpi_read()/apei_read()          -- now OK in interrupt context
    acpi_os_unmap_generic_address()
is equivalent to what atomicio.c provides.

This patch introduces apei_read() and apei_write(), which currently are
functional equivalents of acpi_read() and acpi_write().  This is mainly
proactive, to prevent APEI breakages if acpi_read() and acpi_write()
are ever augmented to support the 'bit_offset' field of GAS, as APEI's
__apei_exec_write_register() precludes splitting up functionality
related to 'bit_offset' and APEI's 'mask' (see its
APEI_EXEC_PRESERVE_REGISTER block).

With apei_read() and apei_write() in place, usages of atomicio routines
are converted to apei_read()/apei_write() and existing calls within
osl.c and the CA, based on the re-factoring that was done in an earlier
patch series - http://marc.info/?l=linux-acpi&m=128769263327206&w=2:
    acpi_pre_map_gar()     -->  acpi_os_map_generic_address()
    acpi_post_unmap_gar()  -->  acpi_os_unmap_generic_address()
    acpi_atomic_read()     -->  apei_read()
    acpi_atomic_write()    -->  apei_write()


Note that acpi_read() and acpi_write() currently use 'bit_width'
for accessing GARs which seems incorrect.  'bit_width' is the size of
the register, while 'access_width' is the size of the access the
processor must generate on the bus.  The 'access_width' may be larger,
for example, if the hardware only supports 32-bit or 64-bit reads.  I
wanted to minimize any possible impacts with this patch series so I
did *not* change this behavior.


Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
---

 drivers/acpi/apei/apei-base.c     |  102 +++++++++++++++++++++++++++++++++++--
 drivers/acpi/apei/apei-internal.h |    3 +
 drivers/acpi/apei/ghes.c          |   10 ++--
 3 files changed, 104 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
index 6154036..f54550a 100644
--- a/drivers/acpi/apei/apei-base.c
+++ b/drivers/acpi/apei/apei-base.c
@@ -34,13 +34,13 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/acpi.h>
+#include <linux/acpi_io.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/kref.h>
 #include <linux/rculist.h>
 #include <linux/interrupt.h>
 #include <linux/debugfs.h>
-#include <acpi/atomicio.h>
 
 #include "apei-internal.h"
 
@@ -70,7 +70,7 @@ int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val)
 {
 	int rc;
 
-	rc = acpi_atomic_read(val, &entry->register_region);
+	rc = apei_read(val, &entry->register_region);
 	if (rc)
 		return rc;
 	*val >>= entry->register_region.bit_offset;
@@ -116,13 +116,13 @@ int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val)
 	val <<= entry->register_region.bit_offset;
 	if (entry->flags & APEI_EXEC_PRESERVE_REGISTER) {
 		u64 valr = 0;
-		rc = acpi_atomic_read(&valr, &entry->register_region);
+		rc = apei_read(&valr, &entry->register_region);
 		if (rc)
 			return rc;
 		valr &= ~(entry->mask << entry->register_region.bit_offset);
 		val |= valr;
 	}
-	rc = acpi_atomic_write(val, &entry->register_region);
+	rc = apei_write(val, &entry->register_region);
 
 	return rc;
 }
@@ -243,7 +243,7 @@ static int pre_map_gar_callback(struct apei_exec_context *ctx,
 	u8 ins = entry->instruction;
 
 	if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
-		return acpi_pre_map_gar(&entry->register_region);
+		return acpi_os_map_generic_address(&entry->register_region);
 
 	return 0;
 }
@@ -276,7 +276,7 @@ static int post_unmap_gar_callback(struct apei_exec_context *ctx,
 	u8 ins = entry->instruction;
 
 	if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
-		acpi_post_unmap_gar(&entry->register_region);
+		acpi_os_unmap_generic_address(&entry->register_region);
 
 	return 0;
 }
@@ -553,6 +553,96 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr)
 	return 0;
 }
 
+/* read GAR in interrupt (including NMI) or process context */
+int apei_read(u64 *val, struct acpi_generic_address *reg)
+{
+	int rc;
+	u64 address;
+	u32 tmp, width = reg->bit_width;
+	acpi_status status;
+
+	rc = apei_check_gar(reg, &address);
+	if (rc)
+		return rc;
+
+	if (width == 64)
+		width = 32;	/* Break into two 32-bit transfers */
+
+	*val = 0;
+	switch(reg->space_id) {
+	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+		status = acpi_os_read_memory((acpi_physical_address)
+					     address, &tmp, width);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+		*val = tmp;
+
+		if (reg->bit_width == 64) {
+			/* Read the top 32 bits */
+			status = acpi_os_read_memory((acpi_physical_address)
+						     (address + 4), &tmp, 32);
+			if (ACPI_FAILURE(status))
+				return -EIO;
+			*val |= ((u64)tmp << 32);
+		}
+		break;
+	case ACPI_ADR_SPACE_SYSTEM_IO:
+		status = acpi_os_read_port(address, (u32 *)val, reg->bit_width);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(apei_read);
+
+/* write GAR in interrupt (including NMI) or process context */
+int apei_write(u64 val, struct acpi_generic_address *reg)
+{
+	int rc;
+	u64 address;
+	u32 width = reg->bit_width;
+	acpi_status status;
+
+	rc = apei_check_gar(reg, &address);
+	if (rc)
+		return rc;
+
+	if (width == 64)
+		width = 32;	/* Break into two 32-bit transfers */
+
+	switch (reg->space_id) {
+	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+		status = acpi_os_write_memory((acpi_physical_address)
+					      address, ACPI_LODWORD(val),
+					      width);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+
+		if (reg->bit_width == 64) {
+			status = acpi_os_write_memory((acpi_physical_address)
+						      (address + 4),
+						      ACPI_HIDWORD(val), 32);
+			if (ACPI_FAILURE(status))
+				return -EIO;
+		}
+		break;
+	case ACPI_ADR_SPACE_SYSTEM_IO:
+		status = acpi_os_write_port(address, val, reg->bit_width);
+		if (ACPI_FAILURE(status))
+			return -EIO;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(apei_write);
+
 static int collect_res_callback(struct apei_exec_context *ctx,
 				struct acpi_whea_header *entry,
 				void *data)
diff --git a/drivers/acpi/apei/apei-internal.h b/drivers/acpi/apei/apei-internal.h
index f57050e..617fb10 100644
--- a/drivers/acpi/apei/apei-internal.h
+++ b/drivers/acpi/apei/apei-internal.h
@@ -68,6 +68,9 @@ static inline int apei_exec_run_optional(struct apei_exec_context *ctx, u8 actio
 /* IP has been set in instruction function */
 #define APEI_EXEC_SET_IP	1
 
+int apei_read(u64 *val, struct acpi_generic_address *reg);
+int apei_write(u64 val, struct acpi_generic_address *reg);
+
 int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val);
 int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val);
 int apei_exec_read_register(struct apei_exec_context *ctx,
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b8e08cb..9d75fbc 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/acpi.h>
+#include <linux/acpi_io.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
 #include <linux/timer.h>
@@ -46,7 +47,6 @@
 #include <linux/llist.h>
 #include <linux/genalloc.h>
 #include <acpi/apei.h>
-#include <acpi/atomicio.h>
 #include <acpi/hed.h>
 #include <asm/mce.h>
 #include <asm/tlbflush.h>
@@ -299,7 +299,7 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
 	if (!ghes)
 		return ERR_PTR(-ENOMEM);
 	ghes->generic = generic;
-	rc = acpi_pre_map_gar(&generic->error_status_address);
+	rc = acpi_os_map_generic_address(&generic->error_status_address);
 	if (rc)
 		goto err_free;
 	error_block_length = generic->error_block_length;
@@ -319,7 +319,7 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
 	return ghes;
 
 err_unmap:
-	acpi_post_unmap_gar(&generic->error_status_address);
+	acpi_os_unmap_generic_address(&generic->error_status_address);
 err_free:
 	kfree(ghes);
 	return ERR_PTR(rc);
@@ -328,7 +328,7 @@ err_free:
 static void ghes_fini(struct ghes *ghes)
 {
 	kfree(ghes->estatus);
-	acpi_post_unmap_gar(&ghes->generic->error_status_address);
+	acpi_os_unmap_generic_address(&ghes->generic->error_status_address);
 }
 
 enum {
@@ -399,7 +399,7 @@ static int ghes_read_estatus(struct ghes *ghes, int silent)
 	u32 len;
 	int rc;
 
-	rc = acpi_atomic_read(&buf_paddr, &g->error_status_address);
+	rc = apei_read(&buf_paddr, &g->error_status_address);
 	if (rc) {
 		if (!silent && printk_ratelimit())
 			pr_warning(FW_WARN GHES_PFX