diff mbox

[v2] hwmon: xgene: access mailbox as RAM

Message ID 3475893.910N1IvcYZ@wuerfel (mailing list archive)
State Accepted
Headers show

Commit Message

Arnd Bergmann Sept. 9, 2016, 8:10 p.m. UTC 
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 endianess 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>
---
v2: use write-back mapping instead of write-thru,
    minor coding style changes


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Comments

hotran Sept. 9, 2016, 8:47 p.m. UTC | #1 
Hi Arnd,

On Fri, Sep 9, 2016 at 1:10 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> 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 endianess 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>
> ---
> v2: use write-back mapping instead of write-thru,
>     minor coding style changes
>
> diff --git a/drivers/hwmon/xgene-hwmon.c b/drivers/hwmon/xgene-hwmon.c
> index bc78a5d10182..e5470bd49067 100644
> --- a/drivers/hwmon/xgene-hwmon.c
> +++ b/drivers/hwmon/xgene-hwmon.c
> @@ -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);
> @@ -652,9 +653,9 @@ 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;
>

Acked-by: Hoan Tran <hotran@apm.com>
Tested-by: Hoan Tran <hotran@apm.com>

Thanks
Hoan
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Guenter Roeck Sept. 9, 2016, 9:56 p.m. UTC | #2 
On Fri, Sep 09, 2016 at 10:10:45PM +0200, Arnd Bergmann wrote:
> 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 endianess 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>

Applied after 's/endianess/endianness/' to make checkpatch happy.

Thanks,
Guenter
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diff mbox

Patch

diff --git a/drivers/hwmon/xgene-hwmon.c b/drivers/hwmon/xgene-hwmon.c
index bc78a5d10182..e5470bd49067 100644
--- a/drivers/hwmon/xgene-hwmon.c
+++ b/drivers/hwmon/xgene-hwmon.c
@@ -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);
@@ -652,9 +653,9 @@  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;