[ARM] 3578/1: AT91RM9200 Clock update

Patch from Andrew Victor

Some updates to the clock infrastructure for the AT91RM9200.

1. Hard-coded values replaced with names defined in at91rm9200_sys.h.
2. Added the four PIO clocks, which are enabled at startup.
3. At startup, disable all unused clocks.
4. Minor bugfix for usage counts associated with MCK. [Patch from David
Brownell]
5. Added at91_clock_associate() function to associate device & function
with a particular clock.  [Patch from David Brownell]
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-at91rm9200/clock.c

@@ -32,8 +32,6 @@
 
 #include "generic.h"
 
-#undef	DEBUG
-
 /*
  * There's a lot more which can be done with clocks, including cpufreq
  * integration, slow clock mode support (for system suspend), letting
@@ -41,7 +39,9 @@
  */
 
 struct clk {
-	const char	*name;
+	const char	*name;		/* unique clock name */
+	const char	*function;	/* function of the clock */
+	struct device	*dev;		/* device associated with function */
 	unsigned long	rate_hz;
 	struct clk	*parent;
 	u32		pmc_mask;
@@ -71,15 +71,14 @@ static struct clk clk32k = {
 };
 static struct clk main_clk = {
 	.name		= "main",
-	.pmc_mask	= 1 << 0,	/* in PMC_SR */
-	.users		= 1,
+	.pmc_mask	= AT91_PMC_MOSCS,	/* in PMC_SR */
 	.id		= 1,
 	.primary	= 1,
 };
 static struct clk plla = {
 	.name		= "plla",
 	.parent		= &main_clk,
-	.pmc_mask	= 1 << 1,	/* in PMC_SR */
+	.pmc_mask	= AT91_PMC_LOCKA,	/* in PMC_SR */
 	.id		= 2,
 	.primary	= 1,
 	.pll		= 1,
@@ -105,7 +104,7 @@ static void pllb_mode(struct clk *clk, int is_on)
 static struct clk pllb = {
 	.name		= "pllb",
 	.parent		= &main_clk,
-	.pmc_mask	= 1 << 2,	/* in PMC_SR */
+	.pmc_mask	= AT91_PMC_LOCKB,	/* in PMC_SR */
 	.mode		= pllb_mode,
 	.id		= 3,
 	.primary	= 1,
@@ -177,8 +176,7 @@ static struct clk pck3 = {
  */
 static struct clk mck = {
 	.name		= "mck",
-	.pmc_mask	= 1 << 3,	/* in PMC_SR */
-	.users		= 1,		/* (must be) always on */
+	.pmc_mask	= AT91_PMC_MCKRDY,	/* in PMC_SR */
 };
 
 static void pmc_periph_mode(struct clk *clk, int is_on)
@@ -249,6 +247,30 @@ static struct clk spi_clk = {
 	.pmc_mask	= 1 << AT91_ID_SPI,
 	.mode		= pmc_periph_mode,
 };
+static struct clk pioA_clk = {
+	.name		= "pioA_clk",
+	.parent		= &mck,
+	.pmc_mask	= 1 << AT91_ID_PIOA,
+	.mode		= pmc_periph_mode,
+};
+static struct clk pioB_clk = {
+	.name		= "pioB_clk",
+	.parent		= &mck,
+	.pmc_mask	= 1 << AT91_ID_PIOB,
+	.mode		= pmc_periph_mode,
+};
+static struct clk pioC_clk = {
+	.name		= "pioC_clk",
+	.parent		= &mck,
+	.pmc_mask	= 1 << AT91_ID_PIOC,
+	.mode		= pmc_periph_mode,
+};
+static struct clk pioD_clk = {
+	.name		= "pioD_clk",
+	.parent		= &mck,
+	.pmc_mask	= 1 << AT91_ID_PIOD,
+	.mode		= pmc_periph_mode,
+};
 
 static struct clk *const clock_list[] = {
 	/* four primary clocks -- MUST BE FIRST! */
@@ -279,21 +301,46 @@ static struct clk *const clock_list[] = {
 	&udc_clk,
 	&twi_clk,
 	&spi_clk,
+	&pioA_clk,
+	&pioB_clk,
+	&pioC_clk,
+	&pioD_clk,
 	// ssc0..ssc2
 	// tc0..tc5
+	// irq0..irq6
 	&ohci_clk,
 	&ether_clk,
 };
 
 
+/*
+ * Associate a particular clock with a function (eg, "uart") and device.
+ * The drivers can then request the same 'function' with several different
+ * devices and not care about which clock name to use.
+ */
+void __init at91_clock_associate(const char *id, struct device *dev, const char *func)
+{
+	struct clk *clk = clk_get(NULL, id);
+
+	if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
+		return;
+
+	clk->function = func;
+	clk->dev = dev;
+}
+
 /* clocks are all static for now; no refcounting necessary */
 struct clk *clk_get(struct device *dev, const char *id)
 {
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(clock_list); i++) {
-		if (strcmp(id, clock_list[i]->name) == 0)
-			return clock_list[i];
+		struct clk *clk = clock_list[i];
+
+		if (strcmp(id, clk->name) == 0)
+			return clk;
+		if (clk->function && (dev == clk->dev) && strcmp(id, clk->function) == 0)
+			return clk;
 	}
 
 	return ERR_PTR(-ENOENT);
@@ -593,6 +640,30 @@ static unsigned __init at91_pll_calc(unsigned main_freq, unsigned out_freq)
 	return 0;
 }
 
+
+/*
+ * Several unused clocks may be active.  Turn them off.
+ */
+static void at91_periphclk_reset(void)
+{
+	unsigned long reg;
+	int i;
+
+	reg = at91_sys_read(AT91_PMC_PCSR);
+
+	for (i = 0; i < ARRAY_SIZE(clock_list); i++) {
+		struct clk	*clk = clock_list[i];
+
+		if (clk->mode != pmc_periph_mode)
+			continue;
+
+		if (clk->users > 0)
+			reg &= ~clk->pmc_mask;
+	}
+
+	at91_sys_write(AT91_PMC_PCDR, reg);
+}
+
 int __init at91_clock_init(unsigned long main_clock)
 {
 	unsigned tmp, freq, mckr;
@@ -626,7 +697,6 @@ int __init at91_clock_init(unsigned long main_clock)
 	 */
 	at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
 	pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
-	at91_sys_write(AT91_PMC_PCDR, (1 << AT91_ID_UHP) | (1 << AT91_ID_UDP));
 	at91_sys_write(AT91_PMC_SCDR, AT91_PMC_UHP | AT91_PMC_UDP);
 	at91_sys_write(AT91_CKGR_PLLBR, 0);
 	at91_sys_write(AT91_PMC_SCER, AT91_PMC_MCKUDP);
@@ -640,11 +710,13 @@ int __init at91_clock_init(unsigned long main_clock)
 	 */
 	mckr = at91_sys_read(AT91_PMC_MCKR);
 	mck.parent = clock_list[mckr & AT91_PMC_CSS];
-	mck.parent->users++;
 	freq = mck.parent->rate_hz;
 	freq /= (1 << ((mckr >> 2) & 3));		/* prescale */
 	mck.rate_hz = freq / (1 + ((mckr >> 8) & 3));	/* mdiv */
 
+	/* MCK and CPU clock are "always on" */
+	clk_enable(&mck);
+
 	printk("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
 		freq / 1000000, (unsigned) mck.rate_hz / 1000000,
 		(unsigned) main_clock / 1000000,
@@ -663,19 +735,28 @@ int __init at91_clock_init(unsigned long main_clock)
 			continue;
 
 		pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
-		parent = clock_list[pckr & 3];
+		parent = clock_list[pckr & AT91_PMC_CSS];
 		clk->parent = parent;
 		clk->rate_hz = parent->rate_hz / (1 << ((pckr >> 2) & 3));
+
+		if (clk->users == 0) {
+			/* not being used, so switch it off */
+			at91_sys_write(AT91_PMC_SCDR, clk->pmc_mask);
+		}
 	}
 #else
-	/* disable unused clocks */
+	/* disable all programmable clocks */
 	at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK0 | AT91_PMC_PCK1 | AT91_PMC_PCK2 | AT91_PMC_PCK3);
-#endif	/* CONFIG_AT91_PROGRAMMABLE_CLOCKS */
+#endif
 
-	/* FIXME several unused clocks may still be active...  provide
-	 * a CONFIG option to turn off all unused clocks at some point
-	 * before driver init starts.
-	 */
+	/* enable the PIO clocks */
+	clk_enable(&pioA_clk);
+	clk_enable(&pioB_clk);
+	clk_enable(&pioC_clk);
+	clk_enable(&pioD_clk);
+
+	/* disable all other unused peripheral clocks */
+	at91_periphclk_reset();
 
 	return 0;
 }