| Message ID | 20230609213716.107339-3-CFSworks@gmail.com |
|---|---|
| State | Superseded |
| Delegated to: | Marek Vasut |
| Headers | show |
| Series | sunxi, usb: Clean up SRAM initialization code | expand |
On Fri, 9 Jun 2023 15:37:16 -0600 Sam Edwards <cfsworks@gmail.com> wrote: Hi, > This is largely a cosmetic change, with one functional distinction: > We are now only setting BIT(0), and no longer clearing BIT(1). > > The A20 manual confirms the purpose and bitwidth of this field, and we > have also been doing it this way for a while in Linux-land: The prior > narrative about this initialization being about configuring a FIFO has > pretty much been debunked for years now. > > This cleanup also adds a TODO comment about runtime discovery > of the SYSCON base, per discussion with Andre. > > Signed-off-by: Sam Edwards <CFSworks@gmail.com> > Cc: Andre Przywara <andre.przywara@arm.com> > --- > drivers/usb/musb-new/sunxi.c | 38 +++++++++++++++++++++++++++--------- > 1 file changed, 29 insertions(+), 9 deletions(-) > > diff --git a/drivers/usb/musb-new/sunxi.c b/drivers/usb/musb-new/sunxi.c > index 1111a67eaf..be7faaa11e 100644 > --- a/drivers/usb/musb-new/sunxi.c > +++ b/drivers/usb/musb-new/sunxi.c > @@ -171,15 +171,29 @@ static void USBC_ForceVbusValidToHigh(__iomem void *base) > musb_writel(base, USBC_REG_o_ISCR, reg_val); > } > > -static void USBC_ConfigFIFO_Base(void) > -{ > - u32 reg_value; > +/****************************************************************************** > + * Non-USBC register access needed for initialization > + ******************************************************************************/ > > - /* config usb fifo, 8kb mode */ > - reg_value = readl(SUNXI_SRAMC_BASE + 0x04); > - reg_value &= ~(0x03 << 0); > - reg_value |= BIT(0); > - writel(reg_value, SUNXI_SRAMC_BASE + 0x04); > +/* > + * A10(s), A13, GR8, A20: > + * switch ownership of SRAM block 'D' to the USB-OTG controller > + */ > +static void sunxi_musb_claim_sram(void) > +{ > + /* > + * TODO: Do not use hardcoded SUNXI_SRAMC_BASE; find the syscon base by > + * traversing this OTG device's `allwinner,sram` FDT property and > + * working upward to the system controller. > + */ > + void *syscon_base = (void *)SUNXI_SRAMC_BASE; Can you pass this in as a parameter, then call the function with SUNXI_SRAMC_BASE, for now? Because syscon_base will become a member of struct sunxi_glue, which we have readily accessible in sunxi_musb_init(). And no need for a comment, I think I will come up with something soon enough. Many thanks! Andre > + > + /* > + * BIT(0) of SRAM_CTRL_REG1 (syscon+0x04) controls SRAM-D ownership: > + * '0' -> exclusive access by CPU > + * '1' -> exclusive access by USB0 > + */ > + setbits_le32(syscon_base + 0x04, BIT(0)); > } > > /****************************************************************************** > @@ -313,7 +327,13 @@ static int sunxi_musb_init(struct musb *musb) > musb->isr = sunxi_musb_interrupt; > > if (glue->cfg->has_sram) { > - USBC_ConfigFIFO_Base(); > + /* > + * This is an older USB-OTG controller that Allwinner did not > + * endow with a dedicated SRAM block; it instead uses SRAM > + * block 'D', ownership of which needs to be handed over by > + * the CPU > + */ > + sunxi_musb_claim_sram(); > } > > USBC_EnableDpDmPullUp(musb->mregs);
diff --git a/drivers/usb/musb-new/sunxi.c b/drivers/usb/musb-new/sunxi.c index 1111a67eaf..be7faaa11e 100644 --- a/drivers/usb/musb-new/sunxi.c +++ b/drivers/usb/musb-new/sunxi.c @@ -171,15 +171,29 @@ static void USBC_ForceVbusValidToHigh(__iomem void *base) musb_writel(base, USBC_REG_o_ISCR, reg_val); } -static void USBC_ConfigFIFO_Base(void) -{ - u32 reg_value; +/****************************************************************************** + * Non-USBC register access needed for initialization + ******************************************************************************/ - /* config usb fifo, 8kb mode */ - reg_value = readl(SUNXI_SRAMC_BASE + 0x04); - reg_value &= ~(0x03 << 0); - reg_value |= BIT(0); - writel(reg_value, SUNXI_SRAMC_BASE + 0x04); +/* + * A10(s), A13, GR8, A20: + * switch ownership of SRAM block 'D' to the USB-OTG controller + */ +static void sunxi_musb_claim_sram(void) +{ + /* + * TODO: Do not use hardcoded SUNXI_SRAMC_BASE; find the syscon base by + * traversing this OTG device's `allwinner,sram` FDT property and + * working upward to the system controller. + */ + void *syscon_base = (void *)SUNXI_SRAMC_BASE; + + /* + * BIT(0) of SRAM_CTRL_REG1 (syscon+0x04) controls SRAM-D ownership: + * '0' -> exclusive access by CPU + * '1' -> exclusive access by USB0 + */ + setbits_le32(syscon_base + 0x04, BIT(0)); } /****************************************************************************** @@ -313,7 +327,13 @@ static int sunxi_musb_init(struct musb *musb) musb->isr = sunxi_musb_interrupt; if (glue->cfg->has_sram) { - USBC_ConfigFIFO_Base(); + /* + * This is an older USB-OTG controller that Allwinner did not + * endow with a dedicated SRAM block; it instead uses SRAM + * block 'D', ownership of which needs to be handed over by + * the CPU + */ + sunxi_musb_claim_sram(); } USBC_EnableDpDmPullUp(musb->mregs);
This is largely a cosmetic change, with one functional distinction: We are now only setting BIT(0), and no longer clearing BIT(1). The A20 manual confirms the purpose and bitwidth of this field, and we have also been doing it this way for a while in Linux-land: The prior narrative about this initialization being about configuring a FIFO has pretty much been debunked for years now. This cleanup also adds a TODO comment about runtime discovery of the SYSCON base, per discussion with Andre. Signed-off-by: Sam Edwards <CFSworks@gmail.com> Cc: Andre Przywara <andre.przywara@arm.com> --- drivers/usb/musb-new/sunxi.c | 38 +++++++++++++++++++++++++++--------- 1 file changed, 29 insertions(+), 9 deletions(-)