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-rw-r--r--drivers/amba/bus.c313
1 files changed, 145 insertions, 168 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 0cb20324da16..32b0e0b930c1 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -130,11 +130,100 @@ static struct attribute *amba_dev_attrs[] = {
};
ATTRIBUTE_GROUPS(amba_dev);
+static int amba_read_periphid(struct amba_device *dev)
+{
+ struct reset_control *rstc;
+ u32 size, pid, cid;
+ void __iomem *tmp;
+ int i, ret;
+
+ ret = dev_pm_domain_attach(&dev->dev, true);
+ if (ret) {
+ dev_dbg(&dev->dev, "can't get PM domain: %d\n", ret);
+ goto err_out;
+ }
+
+ ret = amba_get_enable_pclk(dev);
+ if (ret) {
+ dev_dbg(&dev->dev, "can't get pclk: %d\n", ret);
+ goto err_pm;
+ }
+
+ /*
+ * Find reset control(s) of the amba bus and de-assert them.
+ */
+ rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node);
+ if (IS_ERR(rstc)) {
+ ret = PTR_ERR(rstc);
+ if (ret != -EPROBE_DEFER)
+ dev_err(&dev->dev, "can't get reset: %d\n", ret);
+ goto err_clk;
+ }
+ reset_control_deassert(rstc);
+ reset_control_put(rstc);
+
+ size = resource_size(&dev->res);
+ tmp = ioremap(dev->res.start, size);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto err_clk;
+ }
+
+ /*
+ * Read pid and cid based on size of resource
+ * they are located at end of region
+ */
+ for (pid = 0, i = 0; i < 4; i++)
+ pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) << (i * 8);
+ for (cid = 0, i = 0; i < 4; i++)
+ cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) << (i * 8);
+
+ if (cid == CORESIGHT_CID) {
+ /* set the base to the start of the last 4k block */
+ void __iomem *csbase = tmp + size - 4096;
+
+ dev->uci.devarch = readl(csbase + UCI_REG_DEVARCH_OFFSET);
+ dev->uci.devtype = readl(csbase + UCI_REG_DEVTYPE_OFFSET) & 0xff;
+ }
+
+ if (cid == AMBA_CID || cid == CORESIGHT_CID) {
+ dev->periphid = pid;
+ dev->cid = cid;
+ }
+
+ if (!dev->periphid)
+ ret = -ENODEV;
+
+ iounmap(tmp);
+
+err_clk:
+ amba_put_disable_pclk(dev);
+err_pm:
+ dev_pm_domain_detach(&dev->dev, true);
+err_out:
+ return ret;
+}
+
static int amba_match(struct device *dev, struct device_driver *drv)
{
struct amba_device *pcdev = to_amba_device(dev);
struct amba_driver *pcdrv = to_amba_driver(drv);
+ if (!pcdev->periphid) {
+ int ret = amba_read_periphid(pcdev);
+
+ /*
+ * Returning any error other than -EPROBE_DEFER from bus match
+ * can cause driver registration failure. So, if there's a
+ * permanent failure in reading pid and cid, simply map it to
+ * -EPROBE_DEFER.
+ */
+ if (ret)
+ return -EPROBE_DEFER;
+ dev_set_uevent_suppress(dev, false);
+ kobject_uevent(&dev->kobj, KOBJ_ADD);
+ }
+
/* When driver_override is set, only bind to the matching driver */
if (pcdev->driver_override)
return !strcmp(pcdev->driver_override, drv->name);
@@ -368,6 +457,42 @@ static int __init amba_init(void)
postcore_initcall(amba_init);
+static int amba_proxy_probe(struct amba_device *adev,
+ const struct amba_id *id)
+{
+ WARN(1, "Stub driver should never match any device.\n");
+ return -ENODEV;
+}
+
+static const struct amba_id amba_stub_drv_ids[] = {
+ { 0, 0 },
+};
+
+static struct amba_driver amba_proxy_drv = {
+ .drv = {
+ .name = "amba-proxy",
+ },
+ .probe = amba_proxy_probe,
+ .id_table = amba_stub_drv_ids,
+};
+
+static int __init amba_stub_drv_init(void)
+{
+ if (!IS_ENABLED(CONFIG_MODULES))
+ return 0;
+
+ /*
+ * The amba_match() function will get called only if there is at least
+ * one amba driver registered. If all amba drivers are modules and are
+ * only loaded based on uevents, then we'll hit a chicken-and-egg
+ * situation where amba_match() is waiting on drivers and drivers are
+ * waiting on amba_match(). So, register a stub driver to make sure
+ * amba_match() is called even if no amba driver has been registered.
+ */
+ return amba_driver_register(&amba_proxy_drv);
+}
+late_initcall_sync(amba_stub_drv_init);
+
/**
* amba_driver_register - register an AMBA device driver
* @drv: amba device driver structure
@@ -410,156 +535,6 @@ static void amba_device_release(struct device *dev)
kfree(d);
}
-static int amba_read_periphid(struct amba_device *dev)
-{
- struct reset_control *rstc;
- u32 size, pid, cid;
- void __iomem *tmp;
- int i, ret;
-
- ret = dev_pm_domain_attach(&dev->dev, true);
- if (ret)
- goto err_out;
-
- ret = amba_get_enable_pclk(dev);
- if (ret)
- goto err_pm;
-
- /*
- * Find reset control(s) of the amba bus and de-assert them.
- */
- rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node);
- if (IS_ERR(rstc)) {
- ret = PTR_ERR(rstc);
- if (ret != -EPROBE_DEFER)
- dev_err(&dev->dev, "can't get reset: %d\n", ret);
- goto err_clk;
- }
- reset_control_deassert(rstc);
- reset_control_put(rstc);
-
- size = resource_size(&dev->res);
- tmp = ioremap(dev->res.start, size);
- if (!tmp) {
- ret = -ENOMEM;
- goto err_clk;
- }
-
- /*
- * Read pid and cid based on size of resource
- * they are located at end of region
- */
- for (pid = 0, i = 0; i < 4; i++)
- pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) << (i * 8);
- for (cid = 0, i = 0; i < 4; i++)
- cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) << (i * 8);
-
- if (cid == CORESIGHT_CID) {
- /* set the base to the start of the last 4k block */
- void __iomem *csbase = tmp + size - 4096;
-
- dev->uci.devarch = readl(csbase + UCI_REG_DEVARCH_OFFSET);
- dev->uci.devtype = readl(csbase + UCI_REG_DEVTYPE_OFFSET) & 0xff;
- }
-
- if (cid == AMBA_CID || cid == CORESIGHT_CID) {
- dev->periphid = pid;
- dev->cid = cid;
- }
-
- if (!dev->periphid)
- ret = -ENODEV;
-
- iounmap(tmp);
-
-err_clk:
- amba_put_disable_pclk(dev);
-err_pm:
- dev_pm_domain_detach(&dev->dev, true);
-err_out:
- return ret;
-}
-
-static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
-{
- int ret;
-
- ret = request_resource(parent, &dev->res);
- if (ret)
- goto err_out;
-
- /* Hard-coded primecell ID instead of plug-n-play */
- if (dev->periphid != 0)
- goto skip_probe;
-
- ret = amba_read_periphid(dev);
- if (ret)
- goto err_release;
-
-skip_probe:
- ret = device_add(&dev->dev);
-err_release:
- if (ret)
- release_resource(&dev->res);
-err_out:
- return ret;
-}
-
-/*
- * Registration of AMBA device require reading its pid and cid registers.
- * To do this, the device must be turned on (if it is a part of power domain)
- * and have clocks enabled. However in some cases those resources might not be
- * yet available. Returning EPROBE_DEFER is not a solution in such case,
- * because callers don't handle this special error code. Instead such devices
- * are added to the special list and their registration is retried from
- * periodic worker, until all resources are available and registration succeeds.
- */
-struct deferred_device {
- struct amba_device *dev;
- struct resource *parent;
- struct list_head node;
-};
-
-static LIST_HEAD(deferred_devices);
-static DEFINE_MUTEX(deferred_devices_lock);
-
-static void amba_deferred_retry_func(struct work_struct *dummy);
-static DECLARE_DELAYED_WORK(deferred_retry_work, amba_deferred_retry_func);
-
-#define DEFERRED_DEVICE_TIMEOUT (msecs_to_jiffies(5 * 1000))
-
-static int amba_deferred_retry(void)
-{
- struct deferred_device *ddev, *tmp;
-
- mutex_lock(&deferred_devices_lock);
-
- list_for_each_entry_safe(ddev, tmp, &deferred_devices, node) {
- int ret = amba_device_try_add(ddev->dev, ddev->parent);
-
- if (ret == -EPROBE_DEFER)
- continue;
-
- list_del_init(&ddev->node);
- amba_device_put(ddev->dev);
- kfree(ddev);
- }
-
- mutex_unlock(&deferred_devices_lock);
-
- return 0;
-}
-late_initcall(amba_deferred_retry);
-
-static void amba_deferred_retry_func(struct work_struct *dummy)
-{
- amba_deferred_retry();
-
- if (!list_empty(&deferred_devices))
- schedule_delayed_work(&deferred_retry_work,
- DEFERRED_DEVICE_TIMEOUT);
-}
-
/**
* amba_device_add - add a previously allocated AMBA device structure
* @dev: AMBA device allocated by amba_device_alloc
@@ -571,28 +546,30 @@ static void amba_deferred_retry_func(struct work_struct *dummy)
*/
int amba_device_add(struct amba_device *dev, struct resource *parent)
{
- int ret = amba_device_try_add(dev, parent);
-
- if (ret == -EPROBE_DEFER) {
- struct deferred_device *ddev;
-
- ddev = kmalloc(sizeof(*ddev), GFP_KERNEL);
- if (!ddev)
- return -ENOMEM;
+ int ret;
- ddev->dev = dev;
- ddev->parent = parent;
- ret = 0;
+ ret = request_resource(parent, &dev->res);
+ if (ret)
+ return ret;
- mutex_lock(&deferred_devices_lock);
+ /* If primecell ID isn't hard-coded, figure it out */
+ if (!dev->periphid) {
+ /*
+ * AMBA device uevents require reading its pid and cid
+ * registers. To do this, the device must be on, clocked and
+ * out of reset. However in some cases those resources might
+ * not yet be available. If that's the case, we suppress the
+ * generation of uevents until we can read the pid and cid
+ * registers. See also amba_match().
+ */
+ if (amba_read_periphid(dev))
+ dev_set_uevent_suppress(&dev->dev, true);
+ }
- if (list_empty(&deferred_devices))
- schedule_delayed_work(&deferred_retry_work,
- DEFERRED_DEVICE_TIMEOUT);
- list_add_tail(&ddev->node, &deferred_devices);
+ ret = device_add(&dev->dev);
+ if (ret)
+ release_resource(&dev->res);
- mutex_unlock(&deferred_devices_lock);
- }
return ret;
}
EXPORT_SYMBOL_GPL(amba_device_add);