Commit c7cefce0 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Guenter Roeck
Browse files

hwmon: (xgene) access mailbox as RAM 



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: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarHoan Tran <hotran@apm.com>
Tested-by: default avatarHoan Tran <hotran@apm.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent c0a4b9ec

drivers/hwmon/xgene-hwmon.c

+15 −14
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#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>
@@ -34,7 +35,7 @@ 
#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 */
@@ -126,10 +127,10 @@ 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;

}
@@ -137,7 +138,7 @@ static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask) 
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;
@@ -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);
@@ -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;

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