[PATCH] ARM: i.MX6: boot: detect USB serial downloader more reliable

[Marco Felsch]

On 21-08-11 20:30, Ahmad Fatoum wrote:
> On 11.08.21 19:36, Marco Felsch wrote:
> > The problem with the BootROM is that the SCR registers are not set
> 
> s/SCR/SRC/ ?

of course :)

> > accordingly in case of a failed primary boot. E.g. if the device is
> > configured to boot from an eMMC and the eMMC is empty or image is
> > corrupt, the BootROM goes into 'recovery boot mode' (reference manual
> > Figure 8-1) and the last possible recovery option is the serial
> > downloader. In such case the SRC registers still indicate that the
> > device was booted from an eMMC instead of serial-download.
> > 
> > This commit ports the U-Boot commit [1] with slightly adaptions suggested
> > by Ahmad to Barebox. Also we need to reorder the imx6_init() else we
> > reset the otg-controller to early.
> > 
> > [1] https://source.denx.de/u-boot/u-boot/-/commit/e203dcf23e9eabc2e4f3d0b079457cd1516f2081
> > 
> > Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
> > ---
> >  arch/arm/mach-imx/boot.c  | 27 +++++++++++++++++++++++++++
> >  arch/arm/mach-imx/imx6.c  |  4 ++--
> >  include/soc/fsl/fsl_udc.h | 11 +++++++++++
> >  3 files changed, 40 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
> > index 2b66bbf71e..fcb3c10064 100644
> > --- a/arch/arm/mach-imx/boot.c
> > +++ b/arch/arm/mach-imx/boot.c
> > @@ -8,6 +8,7 @@
> >  #include <magicvar.h>
> >  
> >  #include <io.h>
> > +#include <mach/clock-imx6.h>
> >  #include <mach/generic.h>
> >  #include <mach/imx25-regs.h>
> >  #include <mach/imx27-regs.h>
> > @@ -23,6 +24,7 @@
> >  #include <mach/imx8mq.h>
> >  #include <mach/imx6.h>
> >  
> > +#include <soc/fsl/fsl_udc.h>
> >  
> >  static void
> >  imx_boot_save_loc(void (*get_boot_source)(enum bootsource *, int *))
> > @@ -397,6 +399,11 @@ static u32 imx6_get_src_boot_mode(void __iomem *src_base)
> >  	return readl(src_base + IMX6_SRC_SBMR1);
> >  }
> >  
> > +static inline bool imx6_usboh3_clk_active(void)
> > +{
> > +	return (readl(MXC_CCM_CCGR6) & 0x3) == 0x3;
> > +}
> > +
> >  void imx6_get_boot_source(enum bootsource *src, int *instance)
> >  {
> >  	void __iomem *src_base = IOMEM(MX6_SRC_BASE_ADDR);
> > @@ -410,6 +417,26 @@ void imx6_get_boot_source(enum bootsource *src, int *instance)
> >  
> >  	bootsrc = imx53_bootsource_internal(bootmode);
> >  
> > +	/*
> > +	 * imx6_bootsource_serial() can't detect cases where the boot ROM
> > +	 * decided to use the serial downloader as a fall back (primary
> > +	 * boot source failed).
> > +	 *
> > +	 * Infer that the boot ROM used the USB serial downloader by
> > +	 * checking whether both the UDC and the clock enabling access
> > +	 * to its MMIO region are currently active...
> > +	 * This assumes:
> > +	 * - On fresh boots, PBL doesn't itself start a stopped UDC
> > +	 * - In barebox proper, boot source is saved before the UDC driver
> > +	 *   may enable the UDC
> > +	 */
> > +
> > +	if (imx6_usboh3_clk_active() &&
> > +	    is_chipidea_udc_running(IOMEM(MX6_OTG_BASE_ADDR))) {
> > +		*src = BOOTSOURCE_SERIAL;
> > +		return;
> > +	}
> > +
> >  	if (imx6_bootsource_serial(sbmr2) ||
> >  	    imx6_bootsource_serial_forced(bootsrc)) {
> >  		*src = BOOTSOURCE_SERIAL;
> > diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
> > index 9ccb391384..fa4cb093c3 100644
> > --- a/arch/arm/mach-imx/imx6.c
> > +++ b/arch/arm/mach-imx/imx6.c
> > @@ -205,10 +205,10 @@ int imx6_init(void)
> >  	void __iomem *src = IOMEM(MX6_SRC_BASE_ADDR);
> >  	u64 mx6_uid;
> >  
> > -	imx6_init_lowlevel();
> > -
> >  	imx6_boot_save_loc();
> >  
> > +	imx6_init_lowlevel();
> 
> A comment inside imx6_init_lowlevel hinting at the dependency w.r.t 
> imx6_boot_save_loc would be nice.

Make sense.

Regards,
  Marco

> Apart from these nitpicks:
> 
> Reviewed-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> 
> > +
> >  	mx6_silicon_revision = imx6_cpu_revision();
> >  	mx6_uid = imx6_uid();
> >  
> > diff --git a/include/soc/fsl/fsl_udc.h b/include/soc/fsl/fsl_udc.h
> > index b983f714c5..0b409a9f6b 100644
> > --- a/include/soc/fsl/fsl_udc.h
> > +++ b/include/soc/fsl/fsl_udc.h
> > @@ -1,6 +1,9 @@
> >  #ifndef __FSL_UDC_H
> >  #define __FSL_UDC_H
> >  
> > +#include <linux/types.h>
> > +#include <io.h>
> > +
> >  /* USB DR device mode registers (Little Endian) */
> >  struct usb_dr_device {
> >  	/* Capability register */
> > @@ -380,4 +383,12 @@ int imx_barebox_start_usb(void __iomem *dr, void *dest);
> >  int imx8mm_barebox_load_usb(void *dest);
> >  int imx8mm_barebox_start_usb(void *dest);
> >  
> > +static inline bool is_chipidea_udc_running(void __iomem *dr)
> > +{
> > +	struct usb_dr_device __iomem *dr_regs = dr;
> > +
> > +	return (readl(&dr_regs->usbmode) & USB_MODE_CTRL_MODE_DEVICE)
> > +		&& (readl(&dr_regs->usbcmd) & USB_CMD_RUN_STOP);
> > +}
> > +
> >  #endif /* __FSL_UDC_H */
> > 
> 
> 
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Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |