[ARM] pxa: allow clk aliases

We need to support more than one name+device for a struct clk for a
small number of peripherals.  We do this by re-using struct clk alias
to another struct clk - IOW, if we find that the entry we're using is
an alias, we return the aliased entry not the one we found.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/clock.c

@@ -47,6 +47,9 @@ struct clk *clk_get(struct device *dev, const char *id)
 		clk = p;
 	mutex_unlock(&clocks_mutex);
 
+	if (!IS_ERR(clk) && clk->ops == NULL)
+		clk = clk->other;
+
 	return clk;
 }
 EXPORT_SYMBOL(clk_get);

arch/arm/mach-pxa/clock.h

@@ -15,6 +15,7 @@ struct clk {
 	unsigned int		cken;
 	unsigned int		delay;
 	unsigned int		enabled;
+	struct clk		*other;
 };
 
 #define INIT_CKEN(_name, _cken, _rate, _delay, _dev)	\
@@ -35,6 +36,17 @@ struct clk {
 		.cken	= CKEN_##_cken,			\
 	}
 
+/*
+ * This is a placeholder to alias one clock device+name pair
+ * to another struct clk.
+ */
+#define INIT_CKOTHER(_name, _other, _dev)		\
+	{						\
+		.name	= _name,			\
+		.dev	= _dev,				\
+		.other	= _other,			\
+	}
+
 extern const struct clkops clk_cken_ops;
 
 void clk_cken_enable(struct clk *clk);

arch/arm/mach-pxa/pxa25x.c

@@ -117,6 +117,10 @@ static struct clk pxa25x_hwuart_clk =
 	INIT_CKEN("UARTCLK", HWUART, 14745600, 1, &pxa_device_hwuart.dev)
 ;
 
+/*
+ * PXA 2xx clock declarations. Order is important (see aliases below)
+ * Please be careful not to disrupt the ordering.
+ */
 static struct clk pxa25x_clks[] = {
 	INIT_CK("LCDCLK", LCD, &clk_pxa25x_lcd_ops, &pxa_device_fb.dev),
 	INIT_CKEN("UARTCLK", FFUART, 14745600, 1, &pxa_device_ffuart.dev),
@@ -140,6 +144,8 @@ static struct clk pxa25x_clks[] = {
 	INIT_CKEN("FICPCLK", FICP, 47923000, 0, NULL),
 };
 
+static struct clk gpio7_clk = INIT_CKOTHER("GPIO7_CK", &pxa25x_clks[4], NULL);
+
 #ifdef CONFIG_PM
 
 #define SAVE(x)		sleep_save[SLEEP_SAVE_##x] = x
@@ -311,6 +317,8 @@ static int __init pxa25x_init(void)
 	if (cpu_is_pxa25x())
 		ret = platform_device_register(&pxa_device_hwuart);
 
+	clks_register(&gpio7_clk, 1);
+
 	return ret;
 }