diff mbox series

[v6,2/2] irqchip: irq-qcom-mpm: Support passing a slice of SRAM as reg space

Message ID 20230328-topic-msgram_mpm-v6-2-682e4855b7e2@linaro.org
State New
Headers
Series Resolve MPM register space situation |

Commit Message

Konrad Dybcio Nov. 25, 2023, 2:27 p.m. UTC 
  The MPM hardware is accessible to us from the ARM CPUs through a shared
memory region (RPM MSG RAM) that's also concurrently accessed by other
kinds of cores on the system (like modem, ADSP etc.). Modeling this
relation in a (somewhat) sane manner in the device tree basically
requires us to either present the MPM as a child of said memory region
(which makes little sense, as a mapped memory carveout is not a bus),
define nodes which bleed their register spaces into one another, or
passing their slice of the MSG RAM through some kind of a property.

Go with the third option and add a way to map a region passed through
the "qcom,rpm-msg-ram" property as our register space.

The current way of using 'reg' is preserved for ABI reasons.

Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/irqchip/irq-qcom-mpm.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

Comments

Bryan O'Donoghue Nov. 25, 2023, 3:17 p.m. UTC | #1 
On 25/11/2023 14:27, Konrad Dybcio wrote:
> The MPM hardware is accessible to us from the ARM CPUs through a shared
> memory region (RPM MSG RAM) that's also concurrently accessed by other
> kinds of cores on the system (like modem, ADSP etc.). Modeling this
> relation in a (somewhat) sane manner in the device tree basically
> requires us to either present the MPM as a child of said memory region
> (which makes little sense, as a mapped memory carveout is not a bus),
> define nodes which bleed their register spaces into one another, or
> passing their slice of the MSG RAM through some kind of a property.
> 
> Go with the third option and add a way to map a region passed through
> the "qcom,rpm-msg-ram" property as our register space.
> 
> The current way of using 'reg' is preserved for ABI reasons.
> 
> Acked-by: Shawn Guo <shawn.guo@linaro.org>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
>   drivers/irqchip/irq-qcom-mpm.c | 21 ++++++++++++++++++---
>   1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-qcom-mpm.c b/drivers/irqchip/irq-qcom-mpm.c
> index 7124565234a5..7115e3056aa5 100644
> --- a/drivers/irqchip/irq-qcom-mpm.c
> +++ b/drivers/irqchip/irq-qcom-mpm.c
> @@ -14,6 +14,7 @@
>   #include <linux/mailbox_client.h>
>   #include <linux/module.h>
>   #include <linux/of.h>
> +#include <linux/of_address.h>
>   #include <linux/of_platform.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_domain.h>
> @@ -322,8 +323,10 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
>   	struct device *dev = &pdev->dev;
>   	struct irq_domain *parent_domain;
>   	struct generic_pm_domain *genpd;
> +	struct device_node *msgram_np;
>   	struct qcom_mpm_priv *priv;
>   	unsigned int pin_cnt;
> +	struct resource res;
>   	int i, irq;
>   	int ret;
>   
> @@ -374,9 +377,21 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
>   
>   	raw_spin_lock_init(&priv->lock);
>   
> -	priv->base = devm_platform_ioremap_resource(pdev, 0);
> -	if (IS_ERR(priv->base))
> -		return PTR_ERR(priv->base);
> +	/* If we have a handle to an RPM message ram partition, use it. */
> +	msgram_np = of_parse_phandle(np, "qcom,rpm-msg-ram", 0);
> +	if (msgram_np) {
> +		ret = of_address_to_resource(msgram_np, 0, &res);

You are capturing the return value but doing nothing with it.

One of

if (ret) {
     of_node_put(msgram_np);
     return ret;
}

or just drop the ret =

if you are sure of_address_to_resource() can never return an error for 
your use-case.

Once fixed.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Konrad Dybcio Nov. 25, 2023, 3:41 p.m. UTC | #2 
On 25.11.2023 16:17, Bryan O'Donoghue wrote:
> On 25/11/2023 14:27, Konrad Dybcio wrote:
>> The MPM hardware is accessible to us from the ARM CPUs through a shared
>> memory region (RPM MSG RAM) that's also concurrently accessed by other
>> kinds of cores on the system (like modem, ADSP etc.). Modeling this
>> relation in a (somewhat) sane manner in the device tree basically
>> requires us to either present the MPM as a child of said memory region
>> (which makes little sense, as a mapped memory carveout is not a bus),
>> define nodes which bleed their register spaces into one another, or
>> passing their slice of the MSG RAM through some kind of a property.
>>
>> Go with the third option and add a way to map a region passed through
>> the "qcom,rpm-msg-ram" property as our register space.
>>
>> The current way of using 'reg' is preserved for ABI reasons.
>>
>> Acked-by: Shawn Guo <shawn.guo@linaro.org>
>> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
>> ---
>>   drivers/irqchip/irq-qcom-mpm.c | 21 ++++++++++++++++++---
>>   1 file changed, 18 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-qcom-mpm.c b/drivers/irqchip/irq-qcom-mpm.c
>> index 7124565234a5..7115e3056aa5 100644
>> --- a/drivers/irqchip/irq-qcom-mpm.c
>> +++ b/drivers/irqchip/irq-qcom-mpm.c
>> @@ -14,6 +14,7 @@
>>   #include <linux/mailbox_client.h>
>>   #include <linux/module.h>
>>   #include <linux/of.h>
>> +#include <linux/of_address.h>
>>   #include <linux/of_platform.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/pm_domain.h>
>> @@ -322,8 +323,10 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
>>       struct device *dev = &pdev->dev;
>>       struct irq_domain *parent_domain;
>>       struct generic_pm_domain *genpd;
>> +    struct device_node *msgram_np;
>>       struct qcom_mpm_priv *priv;
>>       unsigned int pin_cnt;
>> +    struct resource res;
>>       int i, irq;
>>       int ret;
>>   @@ -374,9 +377,21 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
>>         raw_spin_lock_init(&priv->lock);
>>   -    priv->base = devm_platform_ioremap_resource(pdev, 0);
>> -    if (IS_ERR(priv->base))
>> -        return PTR_ERR(priv->base);
>> +    /* If we have a handle to an RPM message ram partition, use it. */
>> +    msgram_np = of_parse_phandle(np, "qcom,rpm-msg-ram", 0);
>> +    if (msgram_np) {
>> +        ret = of_address_to_resource(msgram_np, 0, &res);
> 
> You are capturing the return value but doing nothing with it.
Oops you're right
> 
> One of
> 
> if (ret) {
>     of_node_put(msgram_np);
>     return ret;
> }
> 
> or just drop the ret =
> 
> if you are sure of_address_to_resource() can never return an error for your use-case.
Never say never!

Konrad
diff mbox series

Patch

diff --git a/drivers/irqchip/irq-qcom-mpm.c b/drivers/irqchip/irq-qcom-mpm.c
index 7124565234a5..7115e3056aa5 100644
--- a/drivers/irqchip/irq-qcom-mpm.c
+++ b/drivers/irqchip/irq-qcom-mpm.c
@@ -14,6 +14,7 @@ 
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm_domain.h>
@@ -322,8 +323,10 @@  static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
 	struct device *dev = &pdev->dev;
 	struct irq_domain *parent_domain;
 	struct generic_pm_domain *genpd;
+	struct device_node *msgram_np;
 	struct qcom_mpm_priv *priv;
 	unsigned int pin_cnt;
+	struct resource res;
 	int i, irq;
 	int ret;
 
@@ -374,9 +377,21 @@  static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
 
 	raw_spin_lock_init(&priv->lock);
 
-	priv->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(priv->base))
-		return PTR_ERR(priv->base);
+	/* If we have a handle to an RPM message ram partition, use it. */
+	msgram_np = of_parse_phandle(np, "qcom,rpm-msg-ram", 0);
+	if (msgram_np) {
+		ret = of_address_to_resource(msgram_np, 0, &res);
+		/* Don't use devm_ioremap_resource, as we're accessing a shared region. */
+		priv->base = devm_ioremap(dev, res.start, resource_size(&res));
+		of_node_put(msgram_np);
+		if (IS_ERR(priv->base))
+			return PTR_ERR(priv->base);
+	} else {
+		/* Otherwise, fall back to simple MMIO. */
+		priv->base = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(priv->base))
+			return PTR_ERR(priv->base);
+	}
 
 	for (i = 0; i < priv->reg_stride; i++) {
 		qcom_mpm_write(priv, MPM_REG_ENABLE, i, 0);