Re: [PATCH v2 3/4] soc: qcom: pmic_glink: Introduce altmode support

[Neil Armstrong <neil.armstrong@xxxxxxxxxx>]

On 20/01/2023 11:06, Neil Armstrong wrote:
> On 13/01/2023 05:11, Bjorn Andersson wrote:
> > From: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> >
> > With the PMIC GLINK service, the host OS subscribes to USB-C altmode
> > messages, which are sent by the firmware to notify the host OS about
> > state updates and HPD interrupts.
> >
> > The pmic_glink_altmode driver registers for these notifications and
> > propagates the notifications as typec_mux, typec_switch and DRM OOB
> > notifications as necessary to implement DisplayPort altmode support.
> >
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > Signed-off-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
> > ---
> >
> > Changes since v1:
> > - None
> >
> > Johan reported a NULL pointer dereference in
> > drm_kms_helper_hotplug_event() for HPD event being reported while the
> > MSM DRM driver is still being initalized, a separate fix has been sent
> > in hope to remidy this race condition in the MSM driver.
> >
> >   drivers/soc/qcom/Makefile             |   1 +
> >   drivers/soc/qcom/pmic_glink_altmode.c | 477 ++++++++++++++++++++++++++
> >   2 files changed, 478 insertions(+)
> >   create mode 100644 drivers/soc/qcom/pmic_glink_altmode.c
> >
> > diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> > index 29cccac472f3..f30552bf4da7 100644
> > --- a/drivers/soc/qcom/Makefile
> > +++ b/drivers/soc/qcom/Makefile
> > @@ -10,6 +10,7 @@ obj-$(CONFIG_QCOM_MDT_LOADER)    += mdt_loader.o
> >   obj-$(CONFIG_QCOM_OCMEM)    += ocmem.o
> >   obj-$(CONFIG_QCOM_PDR_HELPERS)    += pdr_interface.o
> >   obj-$(CONFIG_QCOM_PMIC_GLINK)    += pmic_glink.o
> > +obj-$(CONFIG_QCOM_PMIC_GLINK)    += pmic_glink_altmode.o
> >   obj-$(CONFIG_QCOM_QMI_HELPERS)    += qmi_helpers.o
> >   qmi_helpers-y    += qmi_encdec.o qmi_interface.o
> >   obj-$(CONFIG_QCOM_RAMP_CTRL)    += ramp_controller.o
> > diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
> > new file mode 100644
> > index 000000000000..8d2d563cb756
> > --- /dev/null
> > +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> > @@ -0,0 +1,477 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (c) 2019-2020, The Linux Foundation. All rights reserved.
> > + * Copyright (c) 2022, Linaro Ltd
> > + */
> > +#include <linux/auxiliary_bus.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/mutex.h>
> > +#include <linux/property.h>
> > +#include <linux/soc/qcom/pdr.h>
> > +#include <drm/drm_bridge.h>
> > +
> > +#include <linux/usb/typec_altmode.h>
> > +#include <linux/usb/typec_dp.h>
> > +#include <linux/usb/typec_mux.h>
> > +
> > +#include <linux/soc/qcom/pmic_glink.h>
> > +
> > +#define PMIC_GLINK_MAX_PORTS    2
> > +
> > +#define USBC_SC8180X_NOTIFY_IND    0x13
> > +#define USBC_CMD_WRITE_REQ      0x15
> > +#define USBC_NOTIFY_IND        0x16
> > +
> > +#define ALTMODE_PAN_EN        0x10
> > +#define ALTMODE_PAN_ACK        0x11
> > +
> > +struct usbc_write_req {
> > +    struct pmic_glink_hdr   hdr;
> > +    __le32 cmd;
> > +    __le32 arg;
> > +    __le32 reserved;
> > +};
> > +
> > +#define NOTIFY_PAYLOAD_SIZE 16
> > +struct usbc_notify {
> > +    struct pmic_glink_hdr hdr;
> > +    char payload[NOTIFY_PAYLOAD_SIZE];
> > +    u32 reserved;
> > +};
> > +
> > +struct usbc_sc8180x_notify {
> > +    struct pmic_glink_hdr hdr;
> > +    __le32 notification;
> > +    __le32 reserved[2];
> > +};
> > +
> > +enum pmic_glink_altmode_pin_assignment {
> > +    DPAM_HPD_OUT,
> > +    DPAM_HPD_A,
> > +    DPAM_HPD_B,
> > +    DPAM_HPD_C,
> > +    DPAM_HPD_D,
> > +    DPAM_HPD_E,
> > +    DPAM_HPD_F,
> > +};
> > +
> > +struct pmic_glink_altmode;
> > +
> > +#define work_to_altmode_port(w) container_of((w), struct pmic_glink_altmode_port, work)
> > +
> > +struct pmic_glink_altmode_port {
> > +    struct pmic_glink_altmode *altmode;
> > +    unsigned int index;
> > +
> > +    struct typec_switch *typec_switch;
> > +    struct typec_mux *typec_mux;
> > +    struct typec_mux_state state;
> > +    struct typec_altmode dp_alt;
> > +
> > +    struct work_struct work;
> > +
> > +    struct drm_bridge bridge;
> > +
> > +    enum typec_orientation orientation;
> > +    u16 svid;
> > +    u8 dp_data;
> > +    u8 mode;
> > +    u8 hpd_state;
> > +    u8 hpd_irq;
> > +};
> > +
> > +#define work_to_altmode(w) container_of((w), struct pmic_glink_altmode, enable_work)
> > +
> > +struct pmic_glink_altmode {
> > +    struct device *dev;
> > +
> > +    unsigned int owner_id;
> > +
> > +    /* To synchronize WRITE_REQ acks */
> > +    struct mutex lock;
> > +
> > +    struct completion pan_ack;
> > +    struct pmic_glink_client *client;
> > +
> > +    struct work_struct enable_work;
> > +
> > +    struct pmic_glink_altmode_port ports[PMIC_GLINK_MAX_PORTS];
> > +};
> > +
> > +static int pmic_glink_altmode_request(struct pmic_glink_altmode *altmode, u32 cmd, u32 arg)
> > +{
> > +    struct usbc_write_req req = {};
> > +    unsigned long left;
> > +    int ret;
> > +
> > +    /*
> > +     * The USBC_CMD_WRITE_REQ ack doesn't identify the request, so wait for
> > +     * one ack at a time.
> > +     */
> > +    mutex_lock(&altmode->lock);
> > +
> > +    req.hdr.owner = cpu_to_le32(altmode->owner_id);
> > +    req.hdr.type = cpu_to_le32(PMIC_GLINK_REQ_RESP);
> > +    req.hdr.opcode = cpu_to_le32(USBC_CMD_WRITE_REQ);
> > +    req.cmd = cpu_to_le32(cmd);
> > +    req.arg = cpu_to_le32(arg);
> > +
> > +    ret = pmic_glink_send(altmode->client, &req, sizeof(req));
> > +    if (ret) {
> > +        dev_err(altmode->dev, "failed to send altmode request: %#x (%d)\n", cmd, ret);
> > +        goto out_unlock;
> > +    }
> > +
> > +    left = wait_for_completion_timeout(&altmode->pan_ack, 5 * HZ);
> > +    if (!left) {
> > +        dev_err(altmode->dev, "timeout waiting for altmode request ack for: %#x\n", cmd);
> > +        ret = -ETIMEDOUT;
> > +    }
> > +
> > +out_unlock:
> > +    mutex_unlock(&altmode->lock);
> > +    return ret;
> > +}
> > +
> > +static void pmic_glink_altmode_enable_dp(struct pmic_glink_altmode *altmode,
> > +                     struct pmic_glink_altmode_port *port,
> > +                     u8 mode, bool hpd_state,
> > +                     bool hpd_irq)
> > +{
> > +    struct typec_displayport_data dp_data = {};
> > +    int ret;
> > +
> > +    dp_data.status = DP_STATUS_ENABLED;
> > +    if (hpd_state)
> > +        dp_data.status |= DP_STATUS_HPD_STATE;
> > +    if (hpd_irq)
> > +        dp_data.status |= DP_STATUS_IRQ_HPD;
> > +    dp_data.conf = DP_CONF_SET_PIN_ASSIGN(mode);
> > +
> > +    port->state.alt = &port->dp_alt;
> > +    port->state.data = &dp_data;
> > +    port->state.mode = TYPEC_MODAL_STATE(mode);
> > +
> > +    ret = typec_mux_set(port->typec_mux, &port->state);
> > +    if (ret)
> > +        dev_err(altmode->dev, "failed to switch mux to DP\n");
> > +}
> > +
> > +static void pmic_glink_altmode_enable_usb(struct pmic_glink_altmode *altmode,
> > +                      struct pmic_glink_altmode_port *port)
> > +{
> > +    int ret;
> > +
> > +    port->state.alt = NULL;
> > +    port->state.data = NULL;
> > +    port->state.mode = TYPEC_STATE_USB;
> > +
> > +    ret = typec_mux_set(port->typec_mux, &port->state);
> > +    if (ret)
> > +        dev_err(altmode->dev, "failed to switch mux to USB\n");
> > +}
> > +
> > +static void pmic_glink_altmode_worker(struct work_struct *work)
> > +{
> > +    struct pmic_glink_altmode_port *alt_port = work_to_altmode_port(work);
> > +    struct pmic_glink_altmode *altmode = alt_port->altmode;
> > +
> > +    typec_switch_set(alt_port->typec_switch, alt_port->orientation);
> > +
> > +    if (alt_port->svid == USB_TYPEC_DP_SID)
> > +        pmic_glink_altmode_enable_dp(altmode, alt_port, alt_port->mode,
> > +                         alt_port->hpd_state, alt_port->hpd_irq);
> > +    else
> > +        pmic_glink_altmode_enable_usb(altmode, alt_port);
> > +
> > +    if (alt_port->hpd_state)
> > +        drm_bridge_hpd_notify(&alt_port->bridge, connector_status_connected);
> > +    else
> > +        drm_bridge_hpd_notify(&alt_port->bridge, connector_status_disconnected);
> > +
> > +    pmic_glink_altmode_request(altmode, ALTMODE_PAN_ACK, alt_port->index);
> > +};
> > +
> > +static enum typec_orientation pmic_glink_altmode_orientation(unsigned int orientation)
> > +{
> > +    if (orientation == 0)
> > +        return TYPEC_ORIENTATION_NORMAL;
> > +    else if (orientation == 1)
> > +        return TYPEC_ORIENTATION_REVERSE;
> > +    else
> > +        return TYPEC_ORIENTATION_NONE;
> > +}
> > +
> > +#define SC8180X_PORT_MASK        0x000000ff
> > +#define SC8180X_ORIENTATION_MASK    0x0000ff00
> > +#define SC8180X_MUX_MASK        0x00ff0000
> > +#define SC8180X_MODE_MASK        0x3f000000
> > +#define SC8180X_HPD_STATE_MASK        0x40000000
> > +#define SC8180X_HPD_IRQ_MASK        0x80000000
> > +
> > +static void pmic_glink_altmode_sc8180xp_notify(struct pmic_glink_altmode *altmode,
> > +                           const void *data, size_t len)
> > +{
> > +    struct pmic_glink_altmode_port *alt_port;
> > +    const struct usbc_sc8180x_notify *msg;
> > +    u32 notification;
> > +    u8 orientation;
> > +    u8 hpd_state;
> > +    u8 hpd_irq;
> > +    u16 svid;
> > +    u8 port;
> > +    u8 mode;
> > +    u8 mux;
> > +
> > +    if (len != sizeof(*msg)) {
> > +        dev_warn(altmode->dev, "invalid length of USBC_NOTIFY indication: %zd\n", len);
> > +        return;
> > +    }
> > +
> > +    msg = data;
> > +    notification = le32_to_cpu(msg->notification);
> > +    port = FIELD_GET(SC8180X_PORT_MASK, notification);
> > +    orientation = FIELD_GET(SC8180X_ORIENTATION_MASK, notification);
> > +    mux = FIELD_GET(SC8180X_MUX_MASK, notification);
> > +    mode = FIELD_GET(SC8180X_MODE_MASK, notification);
> > +    hpd_state = FIELD_GET(SC8180X_HPD_STATE_MASK, notification);
> > +    hpd_irq = FIELD_GET(SC8180X_HPD_IRQ_MASK, notification);
> > +
> > +    svid = mux == 2 ? USB_TYPEC_DP_SID : 0;
> > +
> > +    if (!altmode->ports[port].altmode) {
> > +        dev_dbg(altmode->dev, "notification on undefined port %d\n", port);
> > +        return;
> > +    }
> > +
> > +    alt_port = &altmode->ports[port];
> > +    alt_port->orientation = pmic_glink_altmode_orientation(orientation);
> > +    alt_port->svid = mux == 2 ? USB_TYPEC_DP_SID : 0;
> > +    alt_port->mode = mode;
> > +    alt_port->hpd_state = hpd_state;
> > +    alt_port->hpd_irq = hpd_irq;
> > +    schedule_work(&alt_port->work);
> > +}
> > +
> > +#define SC8280XP_DPAM_MASK    0x3f
> > +#define SC8280XP_HPD_STATE_MASK BIT(6)
> > +#define SC8280XP_HPD_IRQ_MASK    BIT(7)
> > +
> > +static void pmic_glink_altmode_sc8280xp_notify(struct pmic_glink_altmode *altmode,
> > +                           u16 svid, const void *data, size_t len)
> > +{
> > +    struct pmic_glink_altmode_port *alt_port;
> > +    const struct usbc_notify *notify;
> > +    u8 orientation;
> > +    u8 hpd_state;
> > +    u8 hpd_irq;
> > +    u8 mode;
> > +    u8 port;
> > +
> > +    if (len != sizeof(*notify)) {
> > +        dev_warn(altmode->dev, "invalid length USBC_NOTIFY_IND: %zd\n",
> > +             len);
> > +        return;
> > +    }
> > +
> > +    notify = data;
> > +
> > +    port = notify->payload[0];
> > +    orientation = notify->payload[1];
> > +    mode = FIELD_GET(SC8280XP_DPAM_MASK, notify->payload[8]) - DPAM_HPD_A;
> > +    hpd_state = FIELD_GET(SC8280XP_HPD_STATE_MASK, notify->payload[8]);
> > +    hpd_irq = FIELD_GET(SC8280XP_HPD_IRQ_MASK, notify->payload[8]);
> > +
> > +    if (!altmode->ports[port].altmode) {
> > +        dev_dbg(altmode->dev, "notification on undefined port %d\n", port);
> > +        return;
> > +    }
> > +
> > +    alt_port = &altmode->ports[port];
> > +    alt_port->orientation = pmic_glink_altmode_orientation(orientation);
> > +    alt_port->svid = svid;
> > +    alt_port->mode = mode;
> > +    alt_port->hpd_state = hpd_state;
> > +    alt_port->hpd_irq = hpd_irq;
> > +    schedule_work(&alt_port->work);
> > +}
> > +
> > +static void pmic_glink_altmode_callback(const void *data, size_t len, void *priv)
> > +{
> > +    struct pmic_glink_altmode *altmode = priv;
> > +    const struct pmic_glink_hdr *hdr = data;
> > +    u16 opcode;
> > +    u16 svid;
> > +
> > +    opcode = le32_to_cpu(hdr->opcode) & 0xff;
> > +    svid = le32_to_cpu(hdr->opcode) >> 16;
> > +
> > +    switch (opcode) {
> > +    case USBC_CMD_WRITE_REQ:
> > +        complete(&altmode->pan_ack);
> > +        break;
> > +    case USBC_NOTIFY_IND:
> > +        pmic_glink_altmode_sc8280xp_notify(altmode, svid, data, len);
> > +        break;
> > +    case USBC_SC8180X_NOTIFY_IND:
> > +        pmic_glink_altmode_sc8180xp_notify(altmode, data, len);
> > +        break;
> > +    }
> > +}
> > +
> > +static int pmic_glink_altmode_attach(struct drm_bridge *bridge,
> > +                     enum drm_bridge_attach_flags flags)
> > +{
> > +    return flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR ? 0 : -EINVAL;
> > +}
> > +
> > +static const struct drm_bridge_funcs pmic_glink_altmode_bridge_funcs = {
> > +    .attach = pmic_glink_altmode_attach,
> > +};
> > +
> > +static void pmic_glink_altmode_put_mux(void *data)
> > +{
> > +    typec_mux_put(data);
> > +}
> > +
> > +static void pmic_glink_altmode_put_switch(void *data)
> > +{
> > +    typec_switch_put(data);
> > +}
> > +
> > +static void pmic_glink_altmode_enable_worker(struct work_struct *work)
> > +{
> > +    struct pmic_glink_altmode *altmode = work_to_altmode(work);
> > +    int ret;
> > +
> > +    ret = pmic_glink_altmode_request(altmode, ALTMODE_PAN_EN, 0);
> > +    if (ret)
> > +        dev_err(altmode->dev, "failed to request altmode notifications\n");
> > +}
> > +
> > +static void pmic_glink_altmode_pdr_notify(void *priv, int state)
> > +{
> > +    struct pmic_glink_altmode *altmode = priv;
> > +
> > +    if (state == SERVREG_SERVICE_STATE_UP)
> > +        schedule_work(&altmode->enable_work);
> > +}
> > +
> > +static const struct of_device_id pmic_glink_altmode_of_quirks[] = {
> > +    { .compatible = "qcom,sc8180x-pmic-glink", .data = (void *)PMIC_GLINK_OWNER_USBC },
> > +    {}
> > +};
> > +
> > +static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
> > +                    const struct auxiliary_device_id *id)
> > +{
> > +    struct pmic_glink_altmode_port *alt_port;
> > +    struct pmic_glink_altmode *altmode;
> > +    struct typec_altmode_desc mux_desc = {};
> > +    const struct of_device_id *match;
> > +    struct fwnode_handle *fwnode;
> > +    struct device *dev = &adev->dev;
> > +    u32 port;
> > +    int ret;
> > +
> > +    altmode = devm_kzalloc(dev, sizeof(*altmode), GFP_KERNEL);
> > +    if (!altmode)
> > +        return -ENOMEM;
> > +
> > +    altmode->dev = dev;
> > +
> > +    match = of_match_device(pmic_glink_altmode_of_quirks, dev->parent);
> > +    if (match)
> > +        altmode->owner_id = (unsigned long)match->data;
> > +    else
> > +        altmode->owner_id = PMIC_GLINK_OWNER_USBC_PAN;
> > +
> > +    INIT_WORK(&altmode->enable_work, pmic_glink_altmode_enable_worker);
> > +    init_completion(&altmode->pan_ack);
> > +    mutex_init(&altmode->lock);
> > +
> > +    device_for_each_child_node(dev, fwnode) {
> > +        ret = fwnode_property_read_u32(fwnode, "reg", &port);
> > +        if (ret < 0) {
> > +            dev_err(dev, "missing reg property of %pOFn\n", fwnode);
> > +            return ret;
> > +        }
> > +
> > +        if (port >= ARRAY_SIZE(altmode->ports)) {
> > +            dev_warn(dev, "invalid connector number, ignoring\n");
> > +            continue;
> > +        }
> > +
> > +        if (altmode->ports[port].altmode) {
> > +            dev_err(dev, "multiple connector definition for port %u\n", port);
> > +            return -EINVAL;
> > +        }
> > +
> > +        alt_port = &altmode->ports[port];
> > +        alt_port->altmode = altmode;
> > +        alt_port->index = port;
> > +        INIT_WORK(&alt_port->work, pmic_glink_altmode_worker);
> > +
> > +        alt_port->bridge.funcs = &pmic_glink_altmode_bridge_funcs;
> > +        alt_port->bridge.of_node = to_of_node(fwnode);
> > +        alt_port->bridge.ops = DRM_BRIDGE_OP_HPD;
> > +        alt_port->bridge.type = DRM_MODE_CONNECTOR_USB;
> > +
> > +        ret = devm_drm_bridge_add(dev, &alt_port->bridge);
> > +        if (ret)
> > +            return ret;
>
> In my testing, the design of a bridge in the altmode driver made all the probe very fragile,
> meaning that any device that won't probe in the full usb--pmic-glink--display driver would
> prevent the whole to actually probe.
>
> This is why drm_connector_oob_hotplug_event() was used in drivers/usb/typec/altmodes/displayport.c
> and a similar design for cec where both attach to a device so there's no probe dependency.
>
> I think there's a possible simplification here by using :
> of_drm_find_bridge() instead on the endpoint target to get the last bridge,
> or we could probably use the same drm_connector_oob_hotplug_event() but in any way we should
> add missing pieces in drm_bridge_connector and drm/msm/dp/dp_drm.c
>
> First in drm/msm/dp/dp_drm.c, the driver should add the of_node to the DP bridge so it can
> be found from the dp controller node.
>
> Secondly, we could add a fwnode in drm_bridge like in drm_connector and in drm_bridge_connector_init()
> we could set the connector fwnode to the last bridge fwnode + the connector oob event handler.
> In this case the drm_connector_oob_hotplug_event() design should work.
>
> Anyway, I think the bindings is correct, so it's a matter of implementation to avoid delaying the
> display driver probe until the pmic_glink probes entirely.

While looking closely, I don't think we can design differently except moving the bridge code
into a dummy bridge into gpu/drm/bridge, but this won't solve anything but make things even
more complex.

This design follows how generic display connector bridge is designed like in
gpu/drm/bridge/display-connector.c so it's valid.

So for the DRM Bridge part:
Acked-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>

Neil

> Neil
>
> > +
> > +        alt_port->dp_alt.svid = USB_TYPEC_DP_SID;
> > +        alt_port->dp_alt.mode = USB_TYPEC_DP_MODE;
> > +        alt_port->dp_alt.active = 1;
> > +
> > +        mux_desc.svid = USB_TYPEC_DP_SID;
> > +        mux_desc.mode = USB_TYPEC_DP_MODE;
> > +        alt_port->typec_mux = fwnode_typec_mux_get(fwnode, &mux_desc);
> > +        if (IS_ERR(alt_port->typec_mux))
> > +            return dev_err_probe(dev, PTR_ERR(alt_port->typec_mux),
> > +                         "failed to acquire mode-switch for port: %d\n",
> > +                         port);
> > +
> > +        ret = devm_add_action_or_reset(dev, pmic_glink_altmode_put_mux,
> > +                           alt_port->typec_mux);
> > +        if (ret)
> > +            return ret;
> > +
> > +        alt_port->typec_switch = fwnode_typec_switch_get(fwnode);
> > +        if (IS_ERR(alt_port->typec_switch))
> > +            return dev_err_probe(dev, PTR_ERR(alt_port->typec_switch),
> > +                         "failed to acquire orientation-switch for port: %d\n",
> > +                         port);
> > +
> > +        ret = devm_add_action_or_reset(dev, pmic_glink_altmode_put_switch,
> > +                           alt_port->typec_switch);
> > +        if (ret)
> > +            return ret;
> > +    }
> > +
> > +    altmode->client = devm_pmic_glink_register_client(dev,
> > +                              altmode->owner_id,
> > +                              pmic_glink_altmode_callback,
> > +                              pmic_glink_altmode_pdr_notify,
> > +                              altmode);
> > +    return PTR_ERR_OR_ZERO(altmode->client);
> > +}
> > +
> > +static const struct auxiliary_device_id pmic_glink_altmode_id_table[] = {
> > +    { .name = "pmic_glink.altmode", },
> > +    {},
> > +};
> > +MODULE_DEVICE_TABLE(auxiliary, pmic_glink_altmode_id_table);
> > +
> > +static struct auxiliary_driver pmic_glink_altmode_driver = {
> > +    .name = "pmic_glink_altmode",
> > +    .probe = pmic_glink_altmode_probe,
> > +    .id_table = pmic_glink_altmode_id_table,
> > +};
> > +
> > +module_auxiliary_driver(pmic_glink_altmode_driver);
> > +
> > +MODULE_DESCRIPTION("Qualcomm PMIC GLINK Altmode driver");
> > +MODULE_LICENSE("GPL");