[v2] usb: host: ohci-at91: add support to enter suspend using SMC

When Linux is running under OP-TEE, the SFR is set as secured and thus
the AT91_OHCIICR_USB_SUSPEND register isn't accessible. Add a SMC to
do the appropriate call to suspend the controller.
The SMC id is fetched from the device-tree property
"microchip,suspend-smc-id". if present, then the syscon regmap is not
used to enter suspend and a SMC is issued.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
---

Notes:
    Changes in V2:
     - Change check order in ohci_at91_port_suspend()
     - Renamed smc_id to suspend_smc_id for clarity

 drivers/usb/host/ohci-at91.c | 69 ++++++++++++++++++++++++------------
 1 file changed, 46 insertions(+), 23 deletions(-)

On 07.06.2022 16:34, Clément Léger wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> When Linux is running under OP-TEE, the SFR is set as secured and thus
> the AT91_OHCIICR_USB_SUSPEND register isn't accessible. Add a SMC to
> do the appropriate call to suspend the controller.
> The SMC id is fetched from the device-tree property
> "microchip,suspend-smc-id". if present, then the syscon regmap is not
> used to enter suspend and a SMC is issued.
> 
> Signed-off-by: Clément Léger <clement.leger@bootlin.com>

Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>


> ---
> 
> Notes:
>     Changes in V2:
>      - Change check order in ohci_at91_port_suspend()
>      - Renamed smc_id to suspend_smc_id for clarity
> 
>  drivers/usb/host/ohci-at91.c | 69 ++++++++++++++++++++++++------------
>  1 file changed, 46 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
> index a24aea3d2759..98326465e2dc 100644
> --- a/drivers/usb/host/ohci-at91.c
> +++ b/drivers/usb/host/ohci-at91.c
> @@ -13,6 +13,7 @@
>   * This file is licenced under the GPL.
>   */
> 
> +#include <linux/arm-smccc.h>
>  #include <linux/clk.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/gpio/consumer.h>
> @@ -55,6 +56,7 @@ struct ohci_at91_priv {
>         bool clocked;
>         bool wakeup;            /* Saved wake-up state for resume */
>         struct regmap *sfr_regmap;
> +       u32 suspend_smc_id;
>  };
>  /* interface and function clocks; sometimes also an AHB clock */
> 
> @@ -135,6 +137,19 @@ static void at91_stop_hc(struct platform_device *pdev)
> 
>  static void usb_hcd_at91_remove (struct usb_hcd *, struct platform_device *);
> 
> +static u32 at91_dt_suspend_smc(struct device *dev)
> +{
> +       u32 suspend_smc_id;
> +
> +       if (!dev->of_node)
> +               return 0;
> +
> +       if (of_property_read_u32(dev->of_node, "microchip,suspend-smc-id", &suspend_smc_id))
> +               return 0;
> +
> +       return suspend_smc_id;
> +}
> +
>  static struct regmap *at91_dt_syscon_sfr(void)
>  {
>         struct regmap *regmap;
> @@ -215,9 +230,13 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
>                 goto err;
>         }
> 
> -       ohci_at91->sfr_regmap = at91_dt_syscon_sfr();
> -       if (!ohci_at91->sfr_regmap)
> -               dev_dbg(dev, "failed to find sfr node\n");
> +       ohci_at91->suspend_smc_id = at91_dt_suspend_smc(dev);
> +       if (!ohci_at91->suspend_smc_id)  {
> +               dev_dbg(dev, "failed to find sfr suspend smc id, using regmap\n");
> +               ohci_at91->sfr_regmap = at91_dt_syscon_sfr();
> +               if (!ohci_at91->sfr_regmap)
> +                       dev_dbg(dev, "failed to find sfr node\n");
> +       }
> 
>         board = hcd->self.controller->platform_data;
>         ohci = hcd_to_ohci(hcd);
> @@ -303,24 +322,30 @@ static int ohci_at91_hub_status_data(struct usb_hcd *hcd, char *buf)
>         return length;
>  }
> 
> -static int ohci_at91_port_suspend(struct regmap *regmap, u8 set)
> +static int ohci_at91_port_suspend(struct ohci_at91_priv *ohci_at91, u8 set)
>  {
> +       struct regmap *regmap = ohci_at91->sfr_regmap;
>         u32 regval;
>         int ret;
> 
> -       if (!regmap)
> -               return 0;
> +       if (ohci_at91->suspend_smc_id) {
> +               struct arm_smccc_res res;
> 
> -       ret = regmap_read(regmap, AT91_SFR_OHCIICR, &regval);
> -       if (ret)
> -               return ret;
> +               arm_smccc_smc(ohci_at91->suspend_smc_id, set, 0, 0, 0, 0, 0, 0, &res);
> +               if (res.a0)
> +                       return -EINVAL;
> +       } else if (regmap) {
> +               ret = regmap_read(regmap, AT91_SFR_OHCIICR, &regval);
> +               if (ret)
> +                       return ret;
> 
> -       if (set)
> -               regval |= AT91_OHCIICR_USB_SUSPEND;
> -       else
> -               regval &= ~AT91_OHCIICR_USB_SUSPEND;
> +               if (set)
> +                       regval |= AT91_OHCIICR_USB_SUSPEND;
> +               else
> +                       regval &= ~AT91_OHCIICR_USB_SUSPEND;
> 
> -       regmap_write(regmap, AT91_SFR_OHCIICR, regval);
> +               regmap_write(regmap, AT91_SFR_OHCIICR, regval);
> +       }
> 
>         return 0;
>  }
> @@ -357,9 +382,8 @@ static int ohci_at91_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> 
>                 case USB_PORT_FEAT_SUSPEND:
>                         dev_dbg(hcd->self.controller, "SetPortFeat: SUSPEND\n");
> -                       if (valid_port(wIndex) && ohci_at91->sfr_regmap) {
> -                               ohci_at91_port_suspend(ohci_at91->sfr_regmap,
> -                                                      1);
> +                       if (valid_port(wIndex)) {
> +                               ohci_at91_port_suspend(ohci_at91, 1);
>                                 return 0;
>                         }
>                         break;
> @@ -400,9 +424,8 @@ static int ohci_at91_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> 
>                 case USB_PORT_FEAT_SUSPEND:
>                         dev_dbg(hcd->self.controller, "ClearPortFeature: SUSPEND\n");
> -                       if (valid_port(wIndex) && ohci_at91->sfr_regmap) {
> -                               ohci_at91_port_suspend(ohci_at91->sfr_regmap,
> -                                                      0);
> +                       if (valid_port(wIndex)) {
> +                               ohci_at91_port_suspend(ohci_at91, 0);
>                                 return 0;
>                         }
>                         break;
> @@ -630,10 +653,10 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
>                 /* flush the writes */
>                 (void) ohci_readl (ohci, &ohci->regs->control);
>                 msleep(1);
> -               ohci_at91_port_suspend(ohci_at91->sfr_regmap, 1);
> +               ohci_at91_port_suspend(ohci_at91, 1);
>                 at91_stop_clock(ohci_at91);
>         } else {
> -               ohci_at91_port_suspend(ohci_at91->sfr_regmap, 1);
> +               ohci_at91_port_suspend(ohci_at91, 1);
>         }
> 
>         return ret;
> @@ -645,7 +668,7 @@ ohci_hcd_at91_drv_resume(struct device *dev)
>         struct usb_hcd  *hcd = dev_get_drvdata(dev);
>         struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
> 
> -       ohci_at91_port_suspend(ohci_at91->sfr_regmap, 0);
> +       ohci_at91_port_suspend(ohci_at91, 0);
> 
>         if (ohci_at91->wakeup)
>                 disable_irq_wake(hcd->irq);
> --
> 2.36.1
>