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[PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for INTx and private interrupts

Marc Zyngier posted 13 patches 1 month, 1 week ago
[PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for INTx and private interrupts
Posted by Marc Zyngier 1 month, 1 week ago 
T602x seems to have dropped the rather useful SET/CLR accessors
to the masking register.

Instead, let's use the mask register directly, and wrap it with
a brand new spinlock. No, this isn't moving in the right direction.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Tested-by: Janne Grunau <j@jannau.net>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/pci/controller/pcie-apple.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 6d3aa186d9c5f..6b04bf0b41dcc 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -142,6 +142,7 @@ struct apple_pcie {
 };
 
 struct apple_pcie_port {
+	raw_spinlock_t		lock;
 	struct apple_pcie	*pcie;
 	struct device_node	*np;
 	void __iomem		*base;
@@ -261,14 +262,16 @@ static void apple_port_irq_mask(struct irq_data *data)
 {
 	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
 
-	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKSET);
+	guard(raw_spinlock_irqsave)(&port->lock);
+	rmw_set(BIT(data->hwirq), port->base + PORT_INTMSK);
 }
 
 static void apple_port_irq_unmask(struct irq_data *data)
 {
 	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
 
-	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKCLR);
+	guard(raw_spinlock_irqsave)(&port->lock);
+	rmw_clear(BIT(data->hwirq), port->base + PORT_INTMSK);
 }
 
 static bool hwirq_is_intx(unsigned int hwirq)
@@ -387,7 +390,7 @@ static int apple_pcie_port_setup_irq(struct apple_pcie_port *port)
 		return -ENOMEM;
 
 	/* Disable all interrupts */
-	writel_relaxed(~0, port->base + PORT_INTMSKSET);
+	writel_relaxed(~0, port->base + PORT_INTMSK);
 	writel_relaxed(~0, port->base + PORT_INTSTAT);
 
 	irq_set_chained_handler_and_data(irq, apple_port_irq_handler, port);
@@ -537,6 +540,8 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
 	port->pcie = pcie;
 	port->np = np;
 
+	raw_spin_lock_init(&port->lock);
+
 	port->base = devm_platform_ioremap_resource(platform, port->idx + 2);
 	if (IS_ERR(port->base))
 		return PTR_ERR(port->base);
-- 
2.39.2
Re: [PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for INTx and private interrupts
Posted by Bjorn Helgaas 2 weeks, 4 days ago 
On Tue, Apr 01, 2025 at 10:17:07AM +0100, Marc Zyngier wrote:
> T602x seems to have dropped the rather useful SET/CLR accessors
> to the masking register.
> 
> Instead, let's use the mask register directly, and wrap it with
> a brand new spinlock. No, this isn't moving in the right direction.

> @@ -261,14 +262,16 @@ static void apple_port_irq_mask(struct irq_data *data)
>  {
>  	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
>  
> -	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKSET);
> +	guard(raw_spinlock_irqsave)(&port->lock);
> +	rmw_set(BIT(data->hwirq), port->base + PORT_INTMSK);

sparse v0.6.4-39-gce1a6720 complains about this (and similar usage
elsewhere):

  $ make C=2 drivers/pci/
  drivers/pci/controller/pcie-apple.c:311:13: warning: context imbalance in 'apple_port_irq_mask' - wrong count at exit
  drivers/pci/controller/pcie-apple.c:319:13: warning: context imbalance in 'apple_port_irq_unmask' - wrong count at exit

But I guess we just have to live with this for now until somebody
makes sparse smarter:

https://lore.kernel.org/linux-sparse/CAHk-=wiVDZejo_1BhOaR33qb=pny7sWnYtP4JUbRTXkXCkW6jA@mail.gmail.com/

Nothing to do, just "huh".

Bjorn
Re: [PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for INTx and private interrupts
Posted by Marc Zyngier 2 weeks, 4 days ago 
On 2025-04-22 18:41, Bjorn Helgaas wrote:
> On Tue, Apr 01, 2025 at 10:17:07AM +0100, Marc Zyngier wrote:
>> T602x seems to have dropped the rather useful SET/CLR accessors
>> to the masking register.
>> 
>> Instead, let's use the mask register directly, and wrap it with
>> a brand new spinlock. No, this isn't moving in the right direction.
> 
>> @@ -261,14 +262,16 @@ static void apple_port_irq_mask(struct irq_data 
>> *data)
>>  {
>>  	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
>> 
>> -	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKSET);
>> +	guard(raw_spinlock_irqsave)(&port->lock);
>> +	rmw_set(BIT(data->hwirq), port->base + PORT_INTMSK);
> 
> sparse v0.6.4-39-gce1a6720 complains about this (and similar usage
> elsewhere):
> 
>   $ make C=2 drivers/pci/
>   drivers/pci/controller/pcie-apple.c:311:13: warning: context
> imbalance in 'apple_port_irq_mask' - wrong count at exit
>   drivers/pci/controller/pcie-apple.c:319:13: warning: context
> imbalance in 'apple_port_irq_unmask' - wrong count at exit
> 
> But I guess we just have to live with this for now until somebody
> makes sparse smarter:
> 
> https://lore.kernel.org/linux-sparse/CAHk-=wiVDZejo_1BhOaR33qb=pny7sWnYtP4JUbRTXkXCkW6jA@mail.gmail.com/
> 
> Nothing to do, just "huh".

Huh indeed. Pretty sad to see a useful piece of tooling being left
on the curb.

GSoC project?

         M.
-- 
Jazz is not dead. It just smells funny...
Re: [PATCH v3 07/13] PCI: apple: Move away from INTMSK{SET,CLR} for INTx and private interrupts
Posted by Manivannan Sadhasivam 3 weeks, 6 days ago 
On Tue, Apr 01, 2025 at 10:17:07AM +0100, Marc Zyngier wrote:
> T602x seems to have dropped the rather useful SET/CLR accessors
> to the masking register.
> 
> Instead, let's use the mask register directly, and wrap it with
> a brand new spinlock. No, this isn't moving in the right direction.
> 
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
> Tested-by: Janne Grunau <j@jannau.net>
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/controller/pcie-apple.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 6d3aa186d9c5f..6b04bf0b41dcc 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -142,6 +142,7 @@ struct apple_pcie {
>  };
>  
>  struct apple_pcie_port {
> +	raw_spinlock_t		lock;
>  	struct apple_pcie	*pcie;
>  	struct device_node	*np;
>  	void __iomem		*base;
> @@ -261,14 +262,16 @@ static void apple_port_irq_mask(struct irq_data *data)
>  {
>  	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
>  
> -	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKSET);
> +	guard(raw_spinlock_irqsave)(&port->lock);
> +	rmw_set(BIT(data->hwirq), port->base + PORT_INTMSK);
>  }
>  
>  static void apple_port_irq_unmask(struct irq_data *data)
>  {
>  	struct apple_pcie_port *port = irq_data_get_irq_chip_data(data);
>  
> -	writel_relaxed(BIT(data->hwirq), port->base + PORT_INTMSKCLR);
> +	guard(raw_spinlock_irqsave)(&port->lock);
> +	rmw_clear(BIT(data->hwirq), port->base + PORT_INTMSK);
>  }
>  
>  static bool hwirq_is_intx(unsigned int hwirq)
> @@ -387,7 +390,7 @@ static int apple_pcie_port_setup_irq(struct apple_pcie_port *port)
>  		return -ENOMEM;
>  
>  	/* Disable all interrupts */
> -	writel_relaxed(~0, port->base + PORT_INTMSKSET);
> +	writel_relaxed(~0, port->base + PORT_INTMSK);
>  	writel_relaxed(~0, port->base + PORT_INTSTAT);
>  
>  	irq_set_chained_handler_and_data(irq, apple_port_irq_handler, port);
> @@ -537,6 +540,8 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
>  	port->pcie = pcie;
>  	port->np = np;
>  
> +	raw_spin_lock_init(&port->lock);
> +
>  	port->base = devm_platform_ioremap_resource(platform, port->idx + 2);
>  	if (IS_ERR(port->base))
>  		return PTR_ERR(port->base);
> -- 
> 2.39.2
> 

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