drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers
authorDouglas Anderson <dianders@chromium.org>
Fri, 23 Apr 2021 16:58:55 +0000 (09:58 -0700)
committerDouglas Anderson <dianders@chromium.org>
Mon, 3 May 2021 20:21:08 +0000 (13:21 -0700)
Let's use the newly minted aux bus to break up the driver into sub
drivers. We're not doing a full breakup here: all the code is still in
the same file and remains largely untouched. The big goal here of
using sub-drivers is to allow part of our code to finish probing even
if some other code needs to defer. This can solve some chicken-and-egg
problems. Specifically:
- In commit 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for
  delaying prepare()") we had to add a bit of a hack to simpel-panel
  to support HPD showing up late. We can get rid of that hack now
  since the GPIO part of our driver can finish probing early.
- We have a desire to expose our DDC bus to simple-panel (and perhaps
  to a backlight driver?). That will end up with the same
  chicken-and-egg problem. A future patch to move this to a sub-driver
  will fix it.
- If/when we support the PWM functionality present in the bridge chip
  for a backlight we'll end up with another chicken-and-egg
  problem. If we allow the PWM to be a sub-driver too then it solves
  this problem.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.9.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid
drivers/gpu/drm/bridge/Kconfig
drivers/gpu/drm/bridge/ti-sn65dsi86.c

index eef5501..0f4cfbb 100644 (file)
@@ -278,6 +278,7 @@ config DRM_TI_SN65DSI86
        select REGMAP_I2C
        select DRM_PANEL
        select DRM_MIPI_DSI
+       select AUXILIARY_BUS
        help
          Texas Instruments SN65DSI86 DSI to eDP Bridge driver
 
index 5ce6b11..a1db2fb 100644 (file)
@@ -4,6 +4,7 @@
  * datasheet: https://www.ti.com/lit/ds/symlink/sn65dsi86.pdf
  */
 
+#include <linux/auxiliary_bus.h>
 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/debugfs.h>
 
 /**
  * struct ti_sn65dsi86 - Platform data for ti-sn65dsi86 driver.
- * @dev:          Pointer to our device.
+ * @bridge_aux:   AUX-bus sub device for MIPI-to-eDP bridge functionality.
+ * @gpio_aux:     AUX-bus sub device for GPIO controller functionality.
+ *
+ * @dev:          Pointer to the top level (i2c) device.
  * @regmap:       Regmap for accessing i2c.
  * @aux:          Our aux channel.
  * @bridge:       Our bridge.
  *                each other's read-modify-write.
  */
 struct ti_sn65dsi86 {
+       struct auxiliary_device         bridge_aux;
+       struct auxiliary_device         gpio_aux;
+
        struct device                   *dev;
        struct regmap                   *regmap;
        struct drm_dp_aux               aux;
@@ -1137,8 +1144,10 @@ static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = {
        "GPIO1", "GPIO2", "GPIO3", "GPIO4"
 };
 
-static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
+static int ti_sn_gpio_probe(struct auxiliary_device *adev,
+                           const struct auxiliary_device_id *id)
 {
+       struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
        int ret;
 
        /* Only init if someone is going to use us as a GPIO controller */
@@ -1160,20 +1169,41 @@ static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
        pdata->gchip.names = ti_sn_bridge_gpio_names;
        pdata->gchip.ngpio = SN_NUM_GPIOS;
        pdata->gchip.base = -1;
-       ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
+       ret = devm_gpiochip_add_data(&adev->dev, &pdata->gchip, pdata);
        if (ret)
                dev_err(pdata->dev, "can't add gpio chip\n");
 
        return ret;
 }
 
-#else
+static const struct auxiliary_device_id ti_sn_gpio_id_table[] = {
+       { .name = "ti_sn65dsi86.gpio", },
+       {},
+};
 
-static inline int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
+MODULE_DEVICE_TABLE(auxiliary, ti_sn_gpio_id_table);
+
+static struct auxiliary_driver ti_sn_gpio_driver = {
+       .name = "gpio",
+       .probe = ti_sn_gpio_probe,
+       .id_table = ti_sn_gpio_id_table,
+};
+
+static int __init ti_sn_gpio_register(void)
 {
-       return 0;
+       return auxiliary_driver_register(&ti_sn_gpio_driver);
 }
 
+static void __exit ti_sn_gpio_unregister(void)
+{
+       auxiliary_driver_unregister(&ti_sn_gpio_driver);
+}
+
+#else
+
+static inline int ti_sn_gpio_register(void) { return 0; }
+static inline void ti_sn_gpio_unregister(void) {}
+
 #endif
 
 static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
@@ -1225,11 +1255,124 @@ static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
        pdata->ln_polrs = ln_polrs;
 }
 
+static int ti_sn_bridge_probe(struct auxiliary_device *adev,
+                             const struct auxiliary_device_id *id)
+{
+       struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+       struct device_node *np = pdata->dev->of_node;
+       int ret;
+
+       ret = drm_of_find_panel_or_bridge(np, 1, 0, &pdata->panel, NULL);
+       if (ret) {
+               DRM_ERROR("could not find any panel node\n");
+               return ret;
+       }
+
+       ti_sn_bridge_parse_lanes(pdata, np);
+
+       ret = ti_sn_bridge_parse_dsi_host(pdata);
+       if (ret)
+               return ret;
+
+       pdata->aux.name = "ti-sn65dsi86-aux";
+       pdata->aux.dev = pdata->dev;
+       pdata->aux.transfer = ti_sn_aux_transfer;
+       drm_dp_aux_init(&pdata->aux);
+
+       pdata->bridge.funcs = &ti_sn_bridge_funcs;
+       pdata->bridge.of_node = np;
+
+       drm_bridge_add(&pdata->bridge);
+
+       return 0;
+}
+
+static void ti_sn_bridge_remove(struct auxiliary_device *adev)
+{
+       struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+
+       if (!pdata)
+               return;
+
+       if (pdata->dsi) {
+               mipi_dsi_detach(pdata->dsi);
+               mipi_dsi_device_unregister(pdata->dsi);
+       }
+
+       kfree(pdata->edid);
+
+       drm_bridge_remove(&pdata->bridge);
+
+       of_node_put(pdata->host_node);
+}
+
+static const struct auxiliary_device_id ti_sn_bridge_id_table[] = {
+       { .name = "ti_sn65dsi86.bridge", },
+       {},
+};
+
+static struct auxiliary_driver ti_sn_bridge_driver = {
+       .name = "bridge",
+       .probe = ti_sn_bridge_probe,
+       .remove = ti_sn_bridge_remove,
+       .id_table = ti_sn_bridge_id_table,
+};
+
 static void ti_sn65dsi86_runtime_disable(void *data)
 {
        pm_runtime_disable(data);
 }
 
+static void ti_sn65dsi86_uninit_aux(void *data)
+{
+       auxiliary_device_uninit(data);
+}
+
+static void ti_sn65dsi86_delete_aux(void *data)
+{
+       auxiliary_device_delete(data);
+}
+
+/*
+ * AUX bus docs say that a non-NULL release is mandatory, but it makes no
+ * sense for the model used here where all of the aux devices are allocated
+ * in the single shared structure. We'll use this noop as a workaround.
+ */
+static void ti_sn65dsi86_noop(struct device *dev) {}
+
+static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
+                                      struct auxiliary_device *aux,
+                                      const char *name)
+{
+       struct device *dev = pdata->dev;
+       int ret;
+
+       /*
+        * NOTE: It would be nice to set the "of_node" of our children to be
+        * the same "of_node"" that the top-level component has. That doesn't
+        * work, though, since pinctrl will try (and fail) to reserve the
+        * pins again. Until that gets sorted out the children will just need
+        * to look at the of_node of the main device.
+        */
+
+       aux->name = name;
+       aux->dev.parent = dev;
+       aux->dev.release = ti_sn65dsi86_noop;
+       ret = auxiliary_device_init(aux);
+       if (ret)
+               return ret;
+       ret = devm_add_action_or_reset(dev, ti_sn65dsi86_uninit_aux, aux);
+       if (ret)
+               return ret;
+
+       ret = auxiliary_device_add(aux);
+       if (ret)
+               return ret;
+       ret = devm_add_action_or_reset(dev, ti_sn65dsi86_delete_aux, aux);
+
+       return ret;
+}
+
 static int ti_sn65dsi86_probe(struct i2c_client *client,
                              const struct i2c_device_id *id)
 {
@@ -1279,54 +1422,24 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,
 
        ti_sn65dsi86_debugfs_init(pdata);
 
-       ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &pdata->panel, NULL);
-       if (ret) {
-               DRM_ERROR("could not find any panel node\n");
-               return ret;
-       }
-
-       ti_sn_bridge_parse_lanes(pdata, dev->of_node);
-
-       ret = ti_sn_bridge_parse_dsi_host(pdata);
-       if (ret)
-               return ret;
-
-       ret = ti_sn_setup_gpio_controller(pdata);
-       if (ret)
-               return ret;
-
-       pdata->aux.name = "ti-sn65dsi86-aux";
-       pdata->aux.dev = dev;
-       pdata->aux.transfer = ti_sn_aux_transfer;
-       drm_dp_aux_init(&pdata->aux);
-
-       pdata->bridge.funcs = &ti_sn_bridge_funcs;
-       pdata->bridge.of_node = dev->of_node;
-
-       drm_bridge_add(&pdata->bridge);
-
-       return 0;
-}
-
-static int ti_sn65dsi86_remove(struct i2c_client *client)
-{
-       struct ti_sn65dsi86 *pdata = i2c_get_clientdata(client);
-
-       if (!pdata)
-               return -EINVAL;
+       /*
+        * Break ourselves up into a collection of aux devices. The only real
+        * motiviation here is to solve the chicken-and-egg problem of probe
+        * ordering. The bridge wants the panel to be there when it probes.
+        * The panel wants its HPD GPIO (provided by sn65dsi86 on some boards)
+        * when it probes. There will soon be other devices (DDC I2C bus, PWM)
+        * that have the same problem. Having sub-devices allows the some sub
+        * devices to finish probing even if others return -EPROBE_DEFER and
+        * gets us around the problems.
+        */
 
-       if (pdata->dsi) {
-               mipi_dsi_detach(pdata->dsi);
-               mipi_dsi_device_unregister(pdata->dsi);
+       if (IS_ENABLED(CONFIG_OF_GPIO)) {
+               ret = ti_sn65dsi86_add_aux_device(pdata, &pdata->gpio_aux, "gpio");
+               if (ret)
+                       return ret;
        }
 
-       kfree(pdata->edid);
-
-       drm_bridge_remove(&pdata->bridge);
-
-       of_node_put(pdata->host_node);
-
-       return 0;
+       return ti_sn65dsi86_add_aux_device(pdata, &pdata->bridge_aux, "bridge");
 }
 
 static struct i2c_device_id ti_sn65dsi86_id[] = {
@@ -1348,10 +1461,43 @@ static struct i2c_driver ti_sn65dsi86_driver = {
                .pm = &ti_sn65dsi86_pm_ops,
        },
        .probe = ti_sn65dsi86_probe,
-       .remove = ti_sn65dsi86_remove,
        .id_table = ti_sn65dsi86_id,
 };
-module_i2c_driver(ti_sn65dsi86_driver);
+
+static int __init ti_sn65dsi86_init(void)
+{
+       int ret;
+
+       ret = i2c_add_driver(&ti_sn65dsi86_driver);
+       if (ret)
+               return ret;
+
+       ret = ti_sn_gpio_register();
+       if (ret)
+               goto err_main_was_registered;
+
+       ret = auxiliary_driver_register(&ti_sn_bridge_driver);
+       if (ret)
+               goto err_gpio_was_registered;
+
+       return 0;
+
+err_gpio_was_registered:
+       ti_sn_gpio_unregister();
+err_main_was_registered:
+       i2c_del_driver(&ti_sn65dsi86_driver);
+
+       return ret;
+}
+module_init(ti_sn65dsi86_init);
+
+static void __exit ti_sn65dsi86_exit(void)
+{
+       auxiliary_driver_unregister(&ti_sn_bridge_driver);
+       ti_sn_gpio_unregister();
+       i2c_del_driver(&ti_sn65dsi86_driver);
+}
+module_exit(ti_sn65dsi86_exit);
 
 MODULE_AUTHOR("Sandeep Panda <spanda@codeaurora.org>");
 MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");