Re: [PATCH 07/16] ARM: integrator: convert PCI to use generic config accesses

[Bjorn Helgaas <bhelgaas@google.com>]

On Thu, Jan 22, 2015 at 02:33:36PM -0600, Bjorn Helgaas wrote:
> On Mon, Jan 12, 2015 at 01:05:12AM +0100, Linus Walleij wrote:
> > On Sat, Jan 10, 2015 at 10:53 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > > On Saturday 10 January 2015 22:40:22 Linus Walleij wrote:
> > >> >  static int v3_read_config(struct pci_bus *bus, unsigned int devfn, int where,
> > >> >                           int size, u32 *val)
> > >> >  {
> > >> > -       addr = v3_open_config_window(bus, devfn, where);
> > >> > +       int ret = pci_generic_config_read(bus, devfn, where, size, val);
> > >> >         v3_close_config_window();
> > >> > +       return ret;
> > >> >  }
> > >> >
> > >> >  static int v3_write_config(struct pci_bus *bus, unsigned int devfn, int where,
> > >> >                            int size, u32 val)
> > >> >  {
> > >> > +       int ret = pci_generic_config_write(bus, devfn, where, size, val);
> > >> >         v3_close_config_window();
> > >> > -       raw_spin_unlock_irqrestore(&v3_lock, flags);
> > >> > +       return ret;
> > >> >  }
> > >> >
> > >> >  static struct pci_ops pci_v3_ops = {
> > >> > +       .map_bus = v3_open_config_window,
> > >> >         .read   = v3_read_config,
> > >> >         .write  = v3_write_config,
> > >>
> > >> So .map_bus is called before every .read/.write operation I take it.
> > >>
> > >> Wouldn't it be proper to call the v3_close_config_window() from a
> > >> matching .unmap_bus() callback for symmetry?
> > >
> > > It would be nicer for integrator but useless for anything else, so
> > > I'd vote for leaving it the way Rob posted.
> > 
> > OK I buy that, throw in a comment about it in the code if there
> > is some time for iterating the patch.
> 
> Would you prefer something like the following instead?  It keeps the
> v3_open/close symmetry, but it does break apart and duplicate some of the
> logic from v3_open_config_window().

Hearing nothing, I kept Rob's initial version.  It can be tweaked later if
anybody wants to.  I just want to get all this into v3.20.

Bjorn

> commit 3e0c269a560968002298d22ac47bde4bd45aea8e
> Author: Rob Herring <robh@kernel.org>
> Date:   Fri Jan 9 20:34:41 2015 -0600
> 
>     ARM: integrator: Convert PCI to use generic config accessors
>     
>     Convert the integrator PCI driver to use the generic config access
>     functions.
>     
>     This changes accesses from __raw_readX/__raw_writeX to readX/writeX
>     variants.  The spinlock is removed because it is unnecessary.  The config
>     read and write functions are already protected with a spinlock and no
>     access can occur during the .pre_init function.
>     
>     Signed-off-by: Rob Herring <robh@kernel.org>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>     Acked-by: Linus Walleij <linus.walleij@linaro.org>
>     CC: Russell King <linux@arm.linux.org.uk>
>     CC: linux-arm-kernel@lists.infradead.org
> 
> diff --git a/arch/arm/mach-integrator/pci_v3.c b/arch/arm/mach-integrator/pci_v3.c
> index c186a17c2cff..c1098729cf8a 100644
> --- a/arch/arm/mach-integrator/pci_v3.c
> +++ b/arch/arm/mach-integrator/pci_v3.c
> @@ -324,7 +324,7 @@ static u64 pre_mem_pci_sz;
>   * configuration address space, you present the V3 with the following pattern
>   * (which is very nearly a type 1 (except that the lower two bits are 00 and
>   * not 01).   In order for this mapping to work you need to set up one of
> - * the local to PCI aperatures to 16Mbytes in length translating to
> + * the local to PCI apertures to 16Mbytes in length translating to
>   * PCI configuration space starting at 0x0000.0000.
>   *
>   * PCI configuration cycles look like this:
> @@ -356,15 +356,14 @@ static u64 pre_mem_pci_sz;
>   *	 7:2	register number
>   *
>   */
> -static DEFINE_RAW_SPINLOCK(v3_lock);
>  
>  #undef V3_LB_BASE_PREFETCH
>  #define V3_LB_BASE_PREFETCH 0
>  
> -static void __iomem *v3_open_config_window(struct pci_bus *bus,
> -					   unsigned int devfn, int offset)
> +static void v3_open_config_window(struct pci_bus *bus, unsigned int devfn,
> +				  int offset)
>  {
> -	unsigned int address, mapaddress, busnr;
> +	unsigned int mapaddress, busnr;
>  
>  	busnr = bus->number;
>  
> @@ -381,14 +380,10 @@ static void __iomem *v3_open_config_window(struct pci_bus *bus,
>  		/*
>  		 * local bus segment so need a type 0 config cycle
>  		 *
> -		 * build the PCI configuration "address" with one-hot in
> -		 * A31-A11
> -		 *
>  		 * mapaddress:
>  		 *  3:1 = config cycle (101)
>  		 *  0   = PCI A1 & A0 are 0 (0)
>  		 */
> -		address = PCI_FUNC(devfn) << 8;
>  		mapaddress = V3_LB_MAP_TYPE_CONFIG;
>  
>  		if (slot > 12)
> @@ -396,26 +391,15 @@ static void __iomem *v3_open_config_window(struct pci_bus *bus,
>  			 * high order bits are handled by the MAP register
>  			 */
>  			mapaddress |= 1 << (slot - 5);
> -		else
> -			/*
> -			 * low order bits handled directly in the address
> -			 */
> -			address |= 1 << (slot + 11);
>  	} else {
>          	/*
>  		 * not the local bus segment so need a type 1 config cycle
>  		 *
> -		 * address:
> -		 *  23:16 = bus number
> -		 *  15:11 = slot number (7:3 of devfn)
> -		 *  10:8  = func number (2:0 of devfn)
> -		 *
>  		 * mapaddress:
>  		 *  3:1 = config cycle (101)
>  		 *  0   = PCI A1 & A0 from host bus (1)
>  		 */
>  		mapaddress = V3_LB_MAP_TYPE_CONFIG | V3_LB_MAP_AD_LOW_EN;
> -		address = (busnr << 16) | (devfn << 8);
>  	}
>  
>  	/*
> @@ -432,8 +416,6 @@ static void __iomem *v3_open_config_window(struct pci_bus *bus,
>  	v3_writel(V3_LB_BASE1, v3_addr_to_lb_base(conf_mem.start) |
>  			V3_LB_BASE_ADR_SIZE_16MB | V3_LB_BASE_ENABLE);
>  	v3_writew(V3_LB_MAP1, mapaddress);
> -
> -	return PCI_CONFIG_VADDR + address + offset;
>  }
>  
>  static void v3_close_config_window(void)
> @@ -454,70 +436,66 @@ static void v3_close_config_window(void)
>  			V3_LB_BASE_ADR_SIZE_256MB | V3_LB_BASE_ENABLE);
>  }
>  
> -static int v3_read_config(struct pci_bus *bus, unsigned int devfn, int where,
> -			  int size, u32 *val)
> +static void __iomem *v3_map_bus(struct pci_bus *bus,
> +					   unsigned int devfn, int offset)
>  {
> -	void __iomem *addr;
> -	unsigned long flags;
> -	u32 v;
> +	unsigned int busnr = bus->number;
> +	unsigned int address;
>  
> -	raw_spin_lock_irqsave(&v3_lock, flags);
> -	addr = v3_open_config_window(bus, devfn, where);
> -
> -	switch (size) {
> -	case 1:
> -		v = __raw_readb(addr);
> -		break;
> +	if (busnr == 0) {
> +		int slot = PCI_SLOT(devfn);
>  
> -	case 2:
> -		v = __raw_readw(addr);
> -		break;
> +		/*
> +		 * build the PCI configuration "address" with function in
> +		 * A10-A8 and device one-hot in A31-A11
> +		 */
> +		address = PCI_FUNC(devfn) << 8;
>  
> -	default:
> -		v = __raw_readl(addr);
> -		break;
> +		/*
> +		 * high order bits are handled by the MAP register;
> +		 * low order bits handled directly in the address
> +		 */
> +		if (slot <= 12)
> +			address |= 1 << (slot + 11);
> +	} else {
> +		/*
> +		 * not the local bus segment so need a type 1 config cycle
> +		 *
> +		 * address:
> +		 *  23:16 = bus number
> +		 *  15:11 = slot number (7:3 of devfn)
> +		 *  10:8  = func number (2:0 of devfn)
> +		 */
> +		address = (busnr << 16) | (devfn << 8);
>  	}
>  
> -	v3_close_config_window();
> -	raw_spin_unlock_irqrestore(&v3_lock, flags);
> +	return PCI_CONFIG_VADDR + address + offset;
> +}
> +
> +static int v3_read_config(struct pci_bus *bus, unsigned int devfn, int where,
> +			  int size, u32 *val)
> +{
> +	int ret;
>  
> -	*val = v;
> -	return PCIBIOS_SUCCESSFUL;
> +	v3_open_config_window();
> +	ret = pci_generic_config_read(bus, devfn, where, size, val);
> +	v3_close_config_window();
> +	return ret;
>  }
>  
>  static int v3_write_config(struct pci_bus *bus, unsigned int devfn, int where,
>  			   int size, u32 val)
>  {
> -	void __iomem *addr;
> -	unsigned long flags;
> -
> -	raw_spin_lock_irqsave(&v3_lock, flags);
> -	addr = v3_open_config_window(bus, devfn, where);
> -
> -	switch (size) {
> -	case 1:
> -		__raw_writeb((u8)val, addr);
> -		__raw_readb(addr);
> -		break;
> -
> -	case 2:
> -		__raw_writew((u16)val, addr);
> -		__raw_readw(addr);
> -		break;
> -
> -	case 4:
> -		__raw_writel(val, addr);
> -		__raw_readl(addr);
> -		break;
> -	}
> +	int ret;
>  
> +	v3_open_config_window();
> +	ret = pci_generic_config_write(bus, devfn, where, size, val);
>  	v3_close_config_window();
> -	raw_spin_unlock_irqrestore(&v3_lock, flags);
> -
> -	return PCIBIOS_SUCCESSFUL;
> +	return ret;
>  }
>  
>  static struct pci_ops pci_v3_ops = {
> +	.map_bus = v3_map_bus,
>  	.read	= v3_read_config,
>  	.write	= v3_write_config,
>  };
> @@ -672,8 +650,6 @@ static void __init pci_v3_preinit(void)
>  	hook_fault_code(8, v3_pci_fault, SIGBUS, 0, "external abort on non-linefetch");
>  	hook_fault_code(10, v3_pci_fault, SIGBUS, 0, "external abort on non-linefetch");
>  
> -	raw_spin_lock_irqsave(&v3_lock, flags);
> -
>  	/*
>  	 * Unlock V3 registers, but only if they were previously locked.
>  	 */
> @@ -736,8 +712,6 @@ static void __init pci_v3_preinit(void)
>  	v3_writew(V3_LB_CFG, v3_readw(V3_LB_CFG) | (1 << 10));
>  	v3_writeb(V3_LB_IMASK, 0x28);
>  	__raw_writel(3, ap_syscon_base + INTEGRATOR_SC_PCIENABLE_OFFSET);
> -
> -	raw_spin_unlock_irqrestore(&v3_lock, flags);
>  }
>  
>  static void __init pci_v3_postinit(void)