Subject: Re: [PATCH v3 04/27] arm/MSI: Save MSI chip in pci_sys_data

From: Yijing Wang <[email-masked]>
Date: Tue, 21 Oct 2014 09:32:04 +0800

On 2014/10/21 1:21, Lorenzo Pieralisi wrote:
> On Wed, Oct 15, 2014 at 04:06:52AM +0100, Yijing Wang wrote:
>> Saving msi chip in pci_sys_data can make pci bus and
>> devices don't need to know msi chip detail, it also
>> make pci enumeration code be decoupled from msi chip.
>> In fact, all pci devices under the same pci hostbridge
>> share same msi chip. So msi chip should be seen as one
>> of resources or attributes to be initialized in pci host
>> bridge driver. Currently, pci hostbridge drivers create
>> pci_host_bridge in pci_create_root_bus(), and pass arch
>> specific pci sysdata to core pci scan functions. So pci
>> arch sysdata is good place to save msi chip.
>>
>> Signed-off-by: Yijing Wang <[email-masked]>
>> ---
>>  arch/arm/include/asm/mach/pci.h |    6 ++++++
>>  arch/arm/include/asm/pci.h      |    9 +++++++++
>>  arch/arm/kernel/bios32.c        |    3 +++
>>  drivers/pci/msi.c               |    6 ++++++
>>  include/linux/pci.h             |    9 +++++++++
>>  5 files changed, 33 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
>> index 7fc4278..59b0d87 100644
>> --- a/arch/arm/include/asm/mach/pci.h
>> +++ b/arch/arm/include/asm/mach/pci.h
>> @@ -22,6 +22,9 @@ struct hw_pci {
>>  #ifdef CONFIG_PCI_DOMAINS
>>  	int		domain;
>>  #endif
>> +#ifdef CONFIG_PCI_MSI
>> +	struct msi_chip *msi_chip;
>> +#endif
>>  	struct pci_ops	*ops;
>>  	int		nr_controllers;
>>  	void		**private_data;
>> @@ -47,6 +50,9 @@ struct pci_sys_data {
>>  #ifdef CONFIG_PCI_DOMAINS
>>  	int		domain;
>>  #endif
>> +#ifdef CONFIG_PCI_MSI
>> +	struct msi_chip *msi_chip;
>> +#endif
> 
> This struct is defined for ARM only. We are trying to remove dependency on it
> so that we can have a single driver for ARM32 and ARM64 systems without
> pcibios dependency. Why can't we add this msi chip data to the host
> bridge struct instead ? I understand it is all a matter of how to pass
> the pointer to pci_scan_root_bus(), where the bridge is created.
> We could initialize the msi chip on the bridge through the bus pointer
> returned by the pci_scan_root_bus() function.

As mentioned in Patch 0, I will refactor generic pci hostbridge in another series,
We need not only save msi_chip into pci_host_bridge, and other common info, like domain_nr,
resources.

Thanks!
Yijing.

> 
> Thanks,
> Lorenzo
> 
>>  	struct list_head node;
>>  	int		busnr;		/* primary bus number			*/
>>  	u64		mem_offset;	/* bus->cpu memory mapping offset	*/
>> diff --git a/arch/arm/include/asm/pci.h b/arch/arm/include/asm/pci.h
>> index 7e95d85..b562c09 100644
>> --- a/arch/arm/include/asm/pci.h
>> +++ b/arch/arm/include/asm/pci.h
>> @@ -31,6 +31,15 @@ static inline int pci_proc_domain(struct pci_bus *bus)
>>  }
>>  #endif /* CONFIG_PCI_DOMAINS */
>>  
>> +#ifdef CONFIG_PCI_MSI
>> +static inline struct msi_chip *pci_msi_chip(struct pci_bus *bus)
>> +{
>> +	struct pci_sys_data *root = bus->sysdata;
>> +
>> +	return root->msi_chip;
>> +}
>> +#endif
>> +
>>  /*
>>   * The PCI address space does equal the physical memory address space.
>>   * The networking and block device layers use this boolean for bounce
>> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
>> index 17a26c1..a19038d 100644
>> --- a/arch/arm/kernel/bios32.c
>> +++ b/arch/arm/kernel/bios32.c
>> @@ -471,6 +471,9 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
>>  #ifdef CONFIG_PCI_DOMAINS
>>  		sys->domain  = hw->domain;
>>  #endif
>> +#ifdef CONFIG_PCI_MSI
>> +		sys->msi_chip = hw->msi_chip;
>> +#endif
>>  		sys->busnr   = busnr;
>>  		sys->swizzle = hw->swizzle;
>>  		sys->map_irq = hw->map_irq;
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index 22e413c..f11108c 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -35,6 +35,9 @@ int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
>>  	struct msi_chip *chip = dev->bus->msi;
>>  	int err;
>>  
>> +	if (!chip)
>> +		chip = pci_msi_chip(dev->bus);
>> +
>>  	if (!chip || !chip->setup_irq)
>>  		return -EINVAL;
>>  
>> @@ -50,6 +53,9 @@ void __weak arch_teardown_msi_irq(unsigned int irq)
>>  	struct msi_desc *entry = irq_get_msi_desc(irq);
>>  	struct msi_chip *chip = entry->dev->bus->msi;
>>  
>> +	if (!chip)
>> +		chip = pci_msi_chip(entry->dev->bus);
>> +
>>  	if (!chip || !chip->teardown_irq)
>>  		return;
>>  
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 9cd2721..7a48b40 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1433,6 +1433,15 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
>>  
>>  #include <asm/pci.h>
>>  
>> +/* Just avoid compile error, will be clean up later */
>> +#ifdef CONFIG_PCI_MSI
>> +
>> +#ifndef pci_msi_chip
>> +#define pci_msi_chip(bus)	NULL
>> +#endif
>> +
>> +#endif
>> +
>>  /* these helpers provide future and backwards compatibility
>>   * for accessing popular PCI BAR info */
>>  #define pci_resource_start(dev, bar)	((dev)->resource[(bar)].start)
>> -- 
>> 1.7.1
>>
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> 
> 
> .
> 

-- 
Thanks!
Yijing