[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 7/8] xen/arm: introduce vexpress_syscfg
On Tue, 2012-12-18 at 18:46 +0000, Stefano Stabellini wrote: > Introduce a Versatile Express specific function to read/write > motherboard settings. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > --- > xen/arch/arm/Makefile | 1 + > xen/arch/arm/platform_vexpress.c | 97 > +++++++++++++++++++++++++++++++ > xen/include/asm-arm/platform_vexpress.h | 23 +++++++ I wonder if we ought to start a "platforms" subdirs include and arch? This is presumably the first of many. Going the plat-<foo> route seems unnecessary at least at this stage. > +#include <asm/platform_vexpress.h> > +#include <xen/mm.h> > + > +#define DCC_SHIFT 26 > +#define FUNCTION_SHIFT 20 > +#define SITE_SHIFT 16 > +#define POSITION_SHIFT 12 > +#define DEVICE_SHIFT 0 > + > +int vexpress_syscfg(int write, int function, int device, uint32_t *data) > +{ > + uint32_t *syscfg = (uint32_t *) FIXMAP_ADDR(FIXMAP_MISC); > + uint32_t stat; > + int dcc = 0; /* DCC to access */ > + int site = 0; /* motherboard */ > + int position = 0; /* motherboard */ motherboard twice? > + set_fixmap(FIXMAP_MISC, V2M_SYS_MMIO_BASE >> PAGE_SHIFT, DEV_SHARED); > + > + if ( syscfg[V2M_SYS_CFGCTRL] & V2M_SYS_CFG_START ) > + return -1; > + > + /* clear the complete bit in the V2M_SYS_CFGSTAT status register */ Do you mean clear all the bits or specifically the "completion" bit? > + syscfg[V2M_SYS_CFGSTAT] = 0; > + > + if ( write ) > + { > + /* write data */ > + syscfg[V2M_SYS_CFGDATA] = *data; > + > + /* set control register */ > + syscfg[V2M_SYS_CFGCTRL] = V2M_SYS_CFG_START | V2M_SYS_CFG_WRITE | > + (dcc << DCC_SHIFT) | (function << FUNCTION_SHIFT) | > + (site << SITE_SHIFT) | (position << POSITION_SHIFT) | > + (device << DEVICE_SHIFT); Most of this shifting is repeated below, perhaps do it once into a local var to avoid them getting out of sync? > + > + /* wait for complete flag to be set */ > + do { > + stat = syscfg[V2M_SYS_CFGSTAT]; > + dsb(); > + } while ( !(stat & V2M_SYS_CFG_COMPLETE) ); I assume there's no wait-for-event or way to relax this spin loop? Since this is repeated below a helper "wait_for_ocmplet" might be good. Actually, this while bit "set control register" until the error check is common to both the read and write cases, isn't it? > + > + /* check error status and return error flag if set */ > + if ( stat & V2M_SYS_CFG_ERROR ) > + return -1; > + } else { > + /* set control register */ > + syscfg[V2M_SYS_CFGCTRL] = V2M_SYS_CFG_START | (dcc << DCC_SHIFT) | > + (function << FUNCTION_SHIFT) | (site << SITE_SHIFT) | > + (position << POSITION_SHIFT) | (device << DEVICE_SHIFT); > + > + /* wait for complete flag to be set */ > + do { > + stat = syscfg[V2M_SYS_CFGSTAT]; > + dsb(); > + } while ( !(stat & V2M_SYS_CFG_COMPLETE) ); > + > + /* check error status flag and return error flag if set */ > + if ( stat & V2M_SYS_CFG_ERROR ) > + return -1; > + else > + /* read data */ > + *data = syscfg[V2M_SYS_CFGDATA]; > + } > + > + clear_fixmap(FIXMAP_MISC); > + > + return 0; > +} > + > +/* > + * Local variables: > + * mode: C > + * c-set-style: "BSD" > + * c-basic-offset: 4 > + * indent-tabs-mode: nil > + * End: > + */ > diff --git a/xen/include/asm-arm/platform_vexpress.h > b/xen/include/asm-arm/platform_vexpress.h > index 3556af3..407602d 100644 > --- a/xen/include/asm-arm/platform_vexpress.h > +++ b/xen/include/asm-arm/platform_vexpress.h > @@ -6,6 +6,29 @@ > #define V2M_SYS_FLAGSSET (0x30) > #define V2M_SYS_FLAGSCLR (0x34) > > +#define V2M_SYS_CFGDATA (0x00A0/4) > +#define V2M_SYS_CFGCTRL (0x00A4/4) > +#define V2M_SYS_CFGSTAT (0x00A8/4) It'd be better to either define all registers in bytes (as the existing FLAGS*) or words (the new ones) and not to mix the two... > + > +#define V2M_SYS_CFG_START (1<<31) > +#define V2M_SYS_CFG_WRITE (1<<30) > +#define V2M_SYS_CFG_ERROR (1<<1) > +#define V2M_SYS_CFG_COMPLETE (1<<0) > + > +#define V2M_SYS_CFG_OSC_FUNC 1 > +#define V2M_SYS_CFG_OSC0 0 > +#define V2M_SYS_CFG_OSC1 1 > +#define V2M_SYS_CFG_OSC2 2 > +#define V2M_SYS_CFG_OSC3 3 > +#define V2M_SYS_CFG_OSC4 4 > +#define V2M_SYS_CFG_OSC5 5 > + > +#ifndef __ASSEMBLY__ > +#include <xen/inttypes.h> > + > +int vexpress_syscfg(int write, int function, int device, uint32_t *data); > +#endif > + > #endif /* __ASM_ARM_PLATFORM_H */ > /* > * Local variables: _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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