Skip to content

Commit

Permalink
hwmon: (xgene) access mailbox as RAM
Browse files Browse the repository at this point in the history
The newly added hwmon driver fails to build in an allmodconfig
kernel:

      ERROR: "memblock_is_memory" [drivers/hwmon/xgene-hwmon.ko] undefined!

According to comments in the code, the mailbox is a shared memory region,
not a set of MMIO registers, so we should use memremap() for mapping it
instead of ioremap or acpi_os_ioremap, and pointer dereferences instead
of readl/writel.

The driver already uses plain kernel pointers, so it's a bit unusual
to work with functions that operate on __iomem pointers, and this
fixes that part too.

I'm using READ_ONCE/WRITE_ONCE here to keep the existing behavior
regarding the ordering of the accesses from the CPU, but note that
there are no barriers (also unchanged from before).

I'm also keeping the endianness behavior, though I'm unsure whether
the message data was supposed to be in LE32 format in the first
place, it's possible this was meant to be interpreted as a byte
stream instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hoan Tran <hotran@apm.com>
Tested-by: Hoan Tran <hotran@apm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  • Loading branch information
Arnd Bergmann authored and Guenter Roeck committed Sep 9, 2016
1 parent c0a4b9e commit c7cefce
Showing 1 changed file with 15 additions and 14 deletions.
29 changes: 15 additions & 14 deletions drivers/hwmon/xgene-hwmon.c
Original file line number Diff line number Diff line change
Expand Up @@ -27,14 +27,15 @@
#include <linux/dma-mapping.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/kfifo.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <acpi/acpi_io.h>

#include <acpi/pcc.h>

/* SLIMpro message defines */
Expand Down Expand Up @@ -126,18 +127,18 @@ static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask)
{
u16 ret, val;

val = readw_relaxed(addr);
val = le16_to_cpu(READ_ONCE(*addr));
ret = val & mask;
val &= ~mask;
writew_relaxed(val, addr);
WRITE_ONCE(*addr, cpu_to_le16(val));

return ret;
}

static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
{
struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr;
void *ptr = generic_comm_base + 1;
u32 *ptr = (void *)(generic_comm_base + 1);
int rc, i;
u16 val;

Expand All @@ -146,21 +147,21 @@ static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
ctx->resp_pending = true;

/* Write signature for subspace */
writel_relaxed(PCC_SIGNATURE_MASK | ctx->mbox_idx,
&generic_comm_base->signature);
WRITE_ONCE(generic_comm_base->signature,
cpu_to_le32(PCC_SIGNATURE_MASK | ctx->mbox_idx));

/* Write to the shared command region */
writew_relaxed(MSG_TYPE(msg[0]) | PCCC_GENERATE_DB_INT,
&generic_comm_base->command);
WRITE_ONCE(generic_comm_base->command,
cpu_to_le16(MSG_TYPE(msg[0]) | PCCC_GENERATE_DB_INT));

/* Flip CMD COMPLETE bit */
val = readw_relaxed(&generic_comm_base->status);
val = le16_to_cpu(READ_ONCE(generic_comm_base->status));
val &= ~PCCS_CMD_COMPLETE;
writew_relaxed(val, &generic_comm_base->status);
WRITE_ONCE(generic_comm_base->status, cpu_to_le16(val));

/* Copy the message to the PCC comm space */
for (i = 0; i < sizeof(struct slimpro_resp_msg) / 4; i++)
writel_relaxed(msg[i], ptr + i * 4);
WRITE_ONCE(ptr[i], cpu_to_le32(msg[i]));

/* Ring the doorbell */
rc = mbox_send_message(ctx->mbox_chan, msg);
Expand Down Expand Up @@ -689,9 +690,9 @@ static int xgene_hwmon_probe(struct platform_device *pdev)
*/
ctx->comm_base_addr = cppc_ss->base_address;
if (ctx->comm_base_addr) {
ctx->pcc_comm_addr =
acpi_os_ioremap(ctx->comm_base_addr,
cppc_ss->length);
ctx->pcc_comm_addr = memremap(ctx->comm_base_addr,
cppc_ss->length,
MEMREMAP_WB);
} else {
dev_err(&pdev->dev, "Failed to get PCC comm region\n");
rc = -ENODEV;
Expand Down

0 comments on commit c7cefce

Please sign in to comment.