ARM: pxa: ssp: add pxa_ssp_request_of()

Add a function to lookup ssp devices from device tree. This way, users
can reference the ssp devices in order to register to them.

Signed-off-by: Daniel Mack <[e-mail]>
Acked-by: Haojian Zhuang <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

arch/arm/plat-pxa/ssp.c

···
 }
 EXPORT_SYMBOL(pxa_ssp_request);
 
+struct ssp_device *pxa_ssp_request_of(const struct device_node *of_node,
+				      const char *label)
+{
+	struct ssp_device *ssp = NULL;
+
+	mutex_lock(&ssp_lock);
+
+	list_for_each_entry(ssp, &ssp_list, node) {
+		if (ssp->of_node == of_node && ssp->use_count == 0) {
+			ssp->use_count++;
+			ssp->label = label;
+			break;
+		}
+	}
+
+	mutex_unlock(&ssp_lock);
+
+	if (&ssp->node == &ssp_list)
+		return NULL;
+
+	return ssp;
+}
+EXPORT_SYMBOL(pxa_ssp_request_of);
+
 void pxa_ssp_free(struct ssp_device *ssp)
 {
 	mutex_lock(&ssp_lock);
···
 	}
 
 	ssp->use_count = 0;
+	ssp->of_node = dev->of_node;
 
 	mutex_lock(&ssp_lock);
 	list_add(&ssp->node, &ssp_list);

include/linux/pxa2xx_ssp.h

···
 
 #include <linux/list.h>
 #include <linux/io.h>
+#include <linux/of.h>
+
 
 /*
  * SSP Serial Port Registers
···
 	int		irq;
 	int		drcmr_rx;
 	int		drcmr_tx;
+
+	struct device_node	*of_node;
 };
 
 /**
···
 #ifdef CONFIG_ARCH_PXA
 struct ssp_device *pxa_ssp_request(int port, const char *label);
 void pxa_ssp_free(struct ssp_device *);
+struct ssp_device *pxa_ssp_request_of(const struct device_node *of_node,
+				      const char *label);
 #else
 static inline struct ssp_device *pxa_ssp_request(int port, const char *label)
+{
+	return NULL;
+}
+static inline struct ssp_device *pxa_ssp_request_of(const struct device_node *n,
+						    const char *name)
 {
 	return NULL;
 }