[PATCH V2 1/9] uclass: cpu: Add new API to get udevice for current CPU

[Peng Fan <peng.fan@nxp.com>]

When running on SoC with multiple clusters, the boot CPU may
not be fixed, saying booting from cluster A or cluster B.
Add a API that can return the udevice for current boot CPU.
Cpu driver needs to implement is_current_cpu interface for this
feature, otherwise the API only returns the first udevice in
cpu uclass.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Ye Li <ye.li@nxp.com>
---

V2:
 Per Simon's comment,
  - Add cpu_is_current
  - use uclass_foreach_dev_probe
  - Update code comment

 drivers/cpu/cpu-uclass.c | 34 ++++++++++++++++++++++++++++++++++
 include/cpu.h            | 23 +++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/cpu/cpu-uclass.c b/drivers/cpu/cpu-uclass.c
index 457f77b7c8..33d38a0fde 100644
--- a/drivers/cpu/cpu-uclass.c
+++ b/drivers/cpu/cpu-uclass.c
@@ -10,6 +10,7 @@
 #include <errno.h>
 #include <dm/lists.h>
 #include <dm/root.h>
+#include <linux/err.h>
 
 int cpu_probe_all(void)
 {
@@ -34,6 +35,39 @@ int cpu_probe_all(void)
 	return 0;
 }
 
+int cpu_is_current(struct udevice *cpu)
+{
+	struct cpu_ops *ops = cpu_get_ops(cpu);
+
+	if (ops && ops->is_current) {
+		if (ops->is_current(cpu))
+			return 1;
+	}
+
+	return -ENOSYS;
+}
+
+struct udevice *cpu_get_current_dev(void)
+{
+	struct udevice *cpu;
+	int ret;
+
+	uclass_foreach_dev_probe(UCLASS_CPU, cpu) {
+		if (cpu_is_current(cpu) > 0)
+			return cpu;
+	}
+
+	/* If can't find current cpu device, use the first dev instead */
+	ret = uclass_first_device_err(UCLASS_CPU, &cpu);
+	if (ret) {
+		debug("%s: Could not get CPU device (err = %d)\n",
+		      __func__, ret);
+		return NULL;
+	}
+
+	return cpu;
+}
+
 int cpu_get_desc(struct udevice *dev, char *buf, int size)
 {
 	struct cpu_ops *ops = cpu_get_ops(dev);
diff --git a/include/cpu.h b/include/cpu.h
index 6b1b6b37b3..2f283fe244 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -89,6 +89,15 @@ struct cpu_ops {
 	 * @return 0 if OK, -ENOSPC if buffer is too small, other -ve on error
 	 */
 	int (*get_vendor)(struct udevice *dev, char *buf, int size);
+
+	/**
+	 * is_current() - Check if the CPU that U-Boot is currently running from
+	 *
+	 * @dev:	Device to check (UCLASS_CPU)
+	 * @return 1 if the CPU that U-Boot is currently running from, 0
+	 *         if not.
+	 */
+	int (*is_current)(struct udevice *dev);
 };
 
 #define cpu_get_ops(dev)        ((struct cpu_ops *)(dev)->driver->ops)
@@ -137,4 +146,18 @@ int cpu_get_vendor(struct udevice *dev, char *buf, int size);
  */
 int cpu_probe_all(void);
 
+/**
+ * cpu_is_current() - Check if the CPU that U-Boot is currently running from
+ *
+ * Return: 1 if yes, - 0 if not
+ */
+int cpu_is_current(struct udevice *cpu);
+
+/**
+ * cpu_get_current_dev() - Get CPU udevice for current CPU
+ *
+ * Return: udevice if OK, - NULL on error
+ */
+struct udevice *cpu_get_current_dev(void);
+
 #endif
-- 
2.16.4