ENGR00123125 mx23: cleanup and fixes of mach-mx23/clock.c

- add set_rate functionality for x_clk. Added the x_set_rate and x_round_rate functions. A lower x_clk rate will be used for the lowest power 24Mhz state. This implementation to be added later into cpufreq but going ahead and providing the necessary clock driver functionality now. - add enable/disable functionality to ref clocks Assigned the enable and disable function pointers of each of the *_ref_clk tables to the mx23 enable and disable functions. - change lcd clock (default) parent to ref_pix Self explanatory. Previously this was incorrectly assigned directly to the PLL which would cause ref_pix clock to never be gated when not being used which causes very small but unnecessary additional power usage to occur when the LCD is disabled. - add hbus autoslow function to be used by cpufreq Added this function for eventual used by cpufreq driver. - fix pll_enable() delay This delay was changed to match delay requirements given in the mx23 reference manual from the definition of the PLLCTRL0 POWER bitfield. - revise emi_set_rate emi_set_rate had several small issues. The amount of iram it was asking for was set to an arbitrary amount instead of being assigned to the size of the assembly code. Instead, assigning it to the size of the assembly code. When no changes in emiclk speed were being made, we didn't need to spend the time allocating iram, disabling fiqs/irqs, and jumping to the assembly routines Added checks to minimize the time spent in emi_set_rate if then new clock divisors were the same as the old. Added functionality for switching the parent between ref_emi_clk and ref_xtal_clk source based on the clock speed. - added "set_sys_dependent_parent" functionality to allow the reduction some of the peripheral clocks (mainly SSP and GPMI) during the lowest power 24MHz cpu_clk state was needed to allow the PLL to turn off and achieve minimum power usage for that state. The "set_sys_dependent_parent" functionality implements this functionality by checking the cpu speed and changing the parent as needed (but only when the ref count is zero). - other minor cleanup In a couple of locations, I saw the following syntax being used: > -val &= ~(BM_CLKCTRL_FRAC_CPUFRAC << BP_CLKCTRL_FRAC_CPUFRAC); > -val |= clkctrl_frac; This was incorrect because the BM_ definition is already shifted to the correct bitfield location of the register. Shifting it over further by BP_ is a bug. This bug didn't cause problems in these cases because the BP_ value happended to be zero, but needed cleaning up anyway. The mx23_raw_enable was being called without any delays to ensure the clock was ready for use. Added a call to check the clock busy bit to ensure the clock is ready before being used. - Added clock_busy_wait function which replaced all the individual busy_wait handling and properly accounts for clocks with xtal source (which use a separate xtal sourced busy bit). - Cleaned up xtal and rtc clocks/sources functionality. - Added functionality to SSP and GPMI set_rate function to allow changing the parent clock to the xtal if the rate is a factor of 24MHz. Signed-off-by: Robert Lee <robert.lee@freescale.com>
2026-10-20 20:16:04 +00:00 · 2010-05-04 22:13:00 -05:00
parent 19befe2279
commit 0d3e4e8356
4 changed files with 387 additions and 187 deletions
--- a/arch/arm/mach-mx23/clock.c
+++ b/arch/arm/mach-mx23/clock.c
@@ -18,6 +18,7 @@

 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/err.h>
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/clk.h>
@@ -30,17 +31,30 @@
 #include "regs-clkctrl.h"
 #include "regs-digctl.h"

+#include <mach/regs-rtc.h>
 #include <mach/mx23.h>

 #define CLKCTRL_BASE_ADDR IO_ADDRESS(CLKCTRL_PHYS_ADDR)
 #define DIGCTRL_BASE_ADDR IO_ADDRESS(DIGCTL_PHYS_ADDR)
+#define RTC_BASE_ADDR IO_ADDRESS(RTC_PHYS_ADDR)
+
+/* these are the maximum clock speeds that have been
+ * validated to run at the minumum VddD target voltage level for cpu operation
+ * (presently 1.05V target, .975V Brownout).  Higher clock speeds for GPMI and
+ * SSP have not been validated.
+ */
+#define PLL_ENABLED_MAX_CLK_SSP 96000000
+#define PLL_ENABLED_MAX_CLK_GPMI 96000000
+

 /* external clock input */
-static struct clk xtal_clk[];
-static unsigned long xtal_clk_rate[3] = { 24000000, 24000000, 32000 };
 static struct clk pll_clk;
 static struct clk ref_xtal_clk;

+#ifdef DEBUG
+static void print_ref_counts(void);
+#endif
+

 static unsigned long enet_mii_phy_rate;

@@ -62,14 +76,6 @@ static inline int clk_busy_wait(struct clk *clk)
 {
 	int i;

-	/* pll clock requires up to 10us to
-	 * become stable
-	 */
-	if (clk == &pll_clk) {
-		udelay(10);
-		return 0;
-	}
-
 	for (i = 10000000; i; i--)
 		if (!clk_is_busy(clk))
 			break;
@@ -79,6 +85,37 @@ static inline int clk_busy_wait(struct clk *clk)
 		return 0;
 }

+static void local_clk_disable(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk) || !clk->ref)
+		return;
+
+	if ((--clk->ref) & CLK_EN_MASK)
+		return;
+
+	if (clk->disable)
+		clk->disable(clk);
+	local_clk_disable(clk->secondary);
+	local_clk_disable(clk->parent);
+}
+
+static int local_clk_enable(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return -EINVAL;
+
+	if ((clk->ref++) & CLK_EN_MASK)
+		return 0;
+	if (clk->parent)
+		local_clk_enable(clk->parent);
+	if (clk->secondary)
+		local_clk_enable(clk->secondary);
+	if (clk->enable)
+		clk->enable(clk);
+	return 0;
+}
+
+
 static int mx23_raw_enable(struct clk *clk)
 {
 	unsigned int reg;
@@ -87,6 +124,9 @@ static int mx23_raw_enable(struct clk *clk)
 		reg &= ~clk->enable_bits;
 		__raw_writel(reg, clk->enable_reg);
 	}
+	if (clk->busy_reg)
+		clk_busy_wait(clk);
+
 	return 0;
 }

@@ -100,29 +140,14 @@ static void mx23_raw_disable(struct clk *clk)
 	}
 }

-static unsigned long xtal_get_rate(struct clk *clk)
+static unsigned long ref_xtal_get_rate(struct clk *clk)
 {
-	int id = clk - xtal_clk;
-	return xtal_clk_rate[id];
+	return 24000000;
 }

-static struct clk xtal_clk[] = {
-	{
-	 .flags = RATE_FIXED,
-	 .get_rate = xtal_get_rate,
-	 },
-	{
-	 .flags = RATE_FIXED,
-	 .get_rate = xtal_get_rate,
-	 },
-	{
-	 .flags = RATE_FIXED,
-	 .get_rate = xtal_get_rate,
-	 },
-};
-
 static struct clk ref_xtal_clk = {
-	.parent = &xtal_clk[0],
+	.flags = RATE_FIXED,
+	.get_rate = ref_xtal_get_rate,
 };

 static unsigned long pll_get_rate(struct clk *clk);
@@ -146,20 +171,23 @@ static unsigned long pll_get_rate(struct clk *clk)

 static int pll_enable(struct clk *clk)
 {
-	int timeout = 100;
-	unsigned long reg;
+	u32 reg;
+
+	reg = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_PLLCTRL0);
+
+	if ((reg & BM_CLKCTRL_PLLCTRL0_POWER) &&
+		(reg & BM_CLKCTRL_PLLCTRL0_EN_USB_CLKS))
+		return 0;

 	__raw_writel(BM_CLKCTRL_PLLCTRL0_POWER |
 			     BM_CLKCTRL_PLLCTRL0_EN_USB_CLKS,
 			     CLKCTRL_BASE_ADDR + HW_CLKCTRL_PLLCTRL0_SET);
-	do {
-		udelay(10);
-		reg = __raw_readl(CLKCTRL_BASE_ADDR +
-				  HW_CLKCTRL_PLLCTRL1);
-		timeout--;
-	} while ((timeout > 0) && !(reg & BM_CLKCTRL_PLLCTRL1_LOCK));
-	if (timeout <= 0)
-		return -EFAULT;
+	/* only a 10us delay is need.  PLLCTRL1 LOCK bitfied is only a timer
+	 * and is incorrect (excessive).  Per definition of the PLLCTRL0
+	 * POWER field, waiting at least 10us.
+	 */
+	udelay(10);
+
 	return 0;
 }

@@ -210,6 +238,8 @@ static unsigned long ref_cpu_get_rate(struct clk *clk)

 static struct clk ref_cpu_clk = {
 	.parent = &pll_clk,
+	.enable = mx23_raw_enable,
+	.disable = mx23_raw_disable,
 	.get_rate = ref_cpu_get_rate,
 	.round_rate = ref_clk_round_rate,
 	.set_rate = ref_clk_set_rate,
@@ -232,6 +262,8 @@ static unsigned long ref_emi_get_rate(struct clk *clk)

 static struct clk ref_emi_clk = {
 	.parent = &pll_clk,
+	.enable = mx23_raw_enable,
+	.disable = mx23_raw_disable,
 	.get_rate = ref_emi_get_rate,
 	.set_rate = ref_clk_set_rate,
 	.round_rate = ref_clk_round_rate,
@@ -243,10 +275,12 @@ static struct clk ref_emi_clk = {

 static unsigned long ref_io_get_rate(struct clk *clk);
 static struct clk ref_io_clk = {
-	 .parent = &pll_clk,
-	 .get_rate = ref_io_get_rate,
-	 .enable_reg = CLKCTRL_BASE_ADDR + HW_CLKCTRL_FRAC,
-	 .enable_bits = BM_CLKCTRL_FRAC_CLKGATEIO,
+	.parent = &pll_clk,
+	.enable = mx23_raw_enable,
+	.disable = mx23_raw_disable,
+	.get_rate = ref_io_get_rate,
+	.enable_reg = CLKCTRL_BASE_ADDR + HW_CLKCTRL_FRAC,
+	.enable_bits = BM_CLKCTRL_FRAC_CLKGATEIO,
 };

 static unsigned long ref_io_get_rate(struct clk *clk)
@@ -270,6 +304,8 @@ static unsigned long ref_pix_get_rate(struct clk *clk)

 static struct clk ref_pix_clk = {
 	.parent = &pll_clk,
+	.enable = mx23_raw_enable,
+	.disable = mx23_raw_disable,
 	.get_rate = ref_pix_get_rate,
 	.enable_reg = CLKCTRL_BASE_ADDR + HW_CLKCTRL_FRAC,
 	.enable_bits = BM_CLKCTRL_FRAC_CLKGATEPIX,
@@ -334,6 +370,8 @@ static int lcdif_set_rate(struct clk *clk, unsigned long rate)

 	ns_cycle *= 2; /* Fix calculate double frequency */

+
+
 	for (div = 1; div < 256; ++div) {
 		u32 fracdiv;
 		u32 ps_result;
@@ -392,16 +430,9 @@ static int lcdif_set_rate(struct clk *clk, unsigned long rate)
 	__raw_writel(reg_val, clk->scale_reg);

 	/* Wait for divider update */
-	if (clk->busy_reg) {
-		int i;
-		for (i = 10000; i; i--)
-			if (!clk_is_busy(clk))
-				break;
-		if (!i) {
-			ret = -ETIMEDOUT;
-			goto out;
-		}
-	}
+	ret = clk_busy_wait(clk);
+	if (ret)
+		goto out;

 	/* Switch to ref_pix source */
 	reg_val = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_CLKSEQ);
@@ -413,7 +444,7 @@ out:
 }

 static struct clk lcdif_clk = {
-	.parent		= &pll_clk,
+	.parent		= &ref_pix_clk,
 	.enable 	= mx23_raw_enable,
 	.disable 	= mx23_raw_disable,
 	.scale_reg	= CLKCTRL_BASE_ADDR + HW_CLKCTRL_PIX,
@@ -462,8 +493,7 @@ static unsigned long cpu_round_rate(struct clk *clk, unsigned long rate)

 static int cpu_set_rate(struct clk *clk, unsigned long rate)
 {
-	unsigned long root_rate =
-			clk->parent->parent->get_rate(clk->parent->parent);
+	unsigned long root_rate = pll_clk.get_rate(&pll_clk);
 	int ret = -EINVAL;
 	u32 clkctrl_cpu = 1;
 	u32 c = clkctrl_cpu;
@@ -477,9 +507,13 @@ static int cpu_set_rate(struct clk *clk, unsigned long rate)
 	reg_val |= (1 << BP_CLKCTRL_CPU_DIV_XTAL);
 	__raw_writel(reg_val, CLKCTRL_BASE_ADDR+HW_CLKCTRL_CPU);

-	if (rate < 24000000)
+	if (rate < ref_xtal_get_rate(&ref_xtal_clk))
 		return -EINVAL;
-	else if (rate == 24000000) {
+
+	if (rate == clk_get_rate(clk))
+		return 0;
+
+	if (rate == ref_xtal_get_rate(&ref_xtal_clk)) {

 		/* switch to the 24M source */
 		clk_set_parent(clk, &ref_xtal_clk);
@@ -552,8 +586,8 @@ static int cpu_set_rate(struct clk *clk, unsigned long rate)

 		/* prepare Frac div */
 		val = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_FRAC);
-		val &= ~(BM_CLKCTRL_FRAC_CPUFRAC << BP_CLKCTRL_FRAC_CPUFRAC);
-		val |= clkctrl_frac;
+		val &= ~(BM_CLKCTRL_FRAC_CPUFRAC);
+		val |= (clkctrl_frac << BP_CLKCTRL_FRAC_CPUFRAC);

 		/* prepare clkctrl_cpu div*/
 		reg_val = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_CPU);
@@ -577,11 +611,7 @@ static int cpu_set_rate(struct clk *clk, unsigned long rate)
 		 * avoids waiting an extra 10us for every cpu clock
 		 * change between ref_cpu sourced frequencies.
 		 */
-
-		if (pll_clk.ref < 1) {
-			mx23_raw_enable(&pll_clk);
-			clk_busy_wait(&pll_clk);
-		}
+		pll_enable(&pll_clk);
 		pll_clk.ref++;

 		/* switch to XTAL CLK source temparily while
@@ -731,25 +761,99 @@ static unsigned long x_get_rate(struct clk *clk)
 	return clk->parent->get_rate(clk->parent) / reg;
 }

+static unsigned long x_round_rate(struct clk *clk, unsigned long rate)
+{
+	unsigned int root_rate, frac_rate;
+	unsigned int div;
+	root_rate = clk->parent->get_rate(clk->parent);
+	frac_rate = root_rate % rate;
+	div = root_rate / rate;
+	/* while the reference manual specifies that divider
+	 * values up to 1023 are aloud, other critial SoC compents
+	 * require higher x clock values at all times.  Through
+	 * limited testing, the lradc functionality to measure
+	 * the battery voltage and copy this value to the
+	 * power supply requires at least a 64kHz xclk.
+	 * so the divider will be limited to 375.
+	 */
+	if ((div == 0) || (div > 375))
+		return root_rate;
+	if (frac_rate == 0)
+		return rate;
+	else
+		return root_rate / (div + 1);
+}
+
+static int x_set_rate(struct clk *clk, unsigned long rate)
+{
+	unsigned long root_rate;
+	unsigned long round_rate;
+	unsigned int reg, div;
+	root_rate = clk->parent->get_rate(clk->parent);
+
+	if ((!clk->round_rate) || !(clk->scale_reg))
+		return -EINVAL;
+
+	round_rate =  clk->round_rate(clk, rate);
+	div = root_rate / round_rate;
+
+	if (root_rate % round_rate)
+			return -EINVAL;
+
+	reg = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_XBUS);
+	reg &= ~(BM_CLKCTRL_XBUS_DIV_FRAC_EN | BM_CLKCTRL_XBUS_DIV);
+	reg |= BF_CLKCTRL_XBUS_DIV(div);
+	__raw_writel(reg, CLKCTRL_BASE_ADDR + HW_CLKCTRL_XBUS);
+
+	return clk_busy_wait(clk);
+
+}
+
 static struct clk x_clk = {
 	.parent = &ref_xtal_clk,
 	.get_rate = x_get_rate,
+	.set_rate = x_set_rate,
+	.round_rate = x_round_rate,
+	.scale_reg = CLKCTRL_BASE_ADDR + HW_CLKCTRL_XBUS,
+	.busy_reg	= CLKCTRL_BASE_ADDR + HW_CLKCTRL_XBUS,
+	.busy_bits	= 31,
 };

+
+
 static struct clk ana_clk = {
 	.parent = &ref_xtal_clk,
 };

-static unsigned long rtc_get_rate(struct clk *clk)
+
+
+static unsigned long xtal_clock32k_get_rate(struct clk *clk)
 {
-	if (clk->parent == &xtal_clk[2])
-		return clk->parent->get_rate(clk->parent);
-	return clk->parent->get_rate(clk->parent) / 768;
+	if (__raw_readl(RTC_BASE_ADDR + HW_RTC_PERSISTENT0) &
+		BM_RTC_PERSISTENT0_XTAL32_FREQ)
+		return 32000;
+	else
+		return 32768;
 }

-static struct clk rtc_clk = {
-	.parent = &ref_xtal_clk,
-	.get_rate = rtc_get_rate,
+static struct clk xtal_clock32k_clk = {
+	.get_rate = xtal_clock32k_get_rate,
+};
+
+static unsigned long rtc32k_get_rate(struct clk *clk)
+{
+	if (clk->parent == &ref_xtal_clk)
+		/* mx23 reference manual had error.
+		 * fixed divider is 750 not 768
+		 */
+		return clk->parent->get_rate(clk->parent) / 750;
+	else
+		return xtal_clock32k_get_rate(clk);
+}
+
+static struct clk rtc32k_clk = {
+	.parent = &xtal_clock32k_clk,
+	.get_rate = rtc32k_get_rate,
 };

 static unsigned long h_get_rate(struct clk *clk)
@@ -794,15 +898,9 @@ static int h_set_rate(struct clk *clk, unsigned long rate)
 	reg |= BF_CLKCTRL_HBUS_DIV(div);
 	__raw_writel(reg, CLKCTRL_BASE_ADDR + HW_CLKCTRL_HBUS);

-	if (clk->busy_reg) {
-		int i;
-		for (i = 10000; i; i--)
-			if (!clk_is_busy(clk))
-				break;
-		if (!i) {
-			printk(KERN_ERR "couldn't set up AHB divisor\n");
-			return -ETIMEDOUT;
-		}
+	if (clk_busy_wait(clk)) {
+		printk(KERN_ERR "couldn't set up AHB divisor\n");
+		return -EINVAL;
 	}

 	return 0;
@@ -850,34 +948,39 @@ static unsigned long emi_round_rate(struct clk *clk, unsigned long rate)
 	return root_rate / div;
 }

+/* when changing the emi clock, dram access must be
+ * disabled.  Special handling is needed to perform
+ * the emi clock change without touching sdram.
+ */
 static int emi_set_rate(struct clk *clk, unsigned long rate)
 {
 	int ret = 0;

-	if (rate < 24000)
-		return -EINVAL;
-	else {
-		int i;
-		struct mxs_emi_scaling_data sc_data;
-		unsigned long iram_phy;
-		int (*scale)(struct mxs_emi_scaling_data *) =
-			iram_alloc(0x1000, &iram_phy);
+	struct mxs_emi_scaling_data sc_data;

-		unsigned long clkctrl_emi;
-		unsigned long clkctrl_frac;
-		int div = 1;
-		unsigned long root_rate =
-			clk->parent->parent->get_rate(clk->parent->parent);
-		if (NULL == scale) {
-			pr_err("%s Not enough iram\n", __func__);
-			return -ENOMEM;
-		}
-		/*
-		 * We've been setting div to HW_CLKCTRL_CPU_RD() & 0x3f so far.
-		 * TODO: verify 1 is still valid.
-		 */
-		if (!mxs_ram_funcs_sz)
-			goto out;
+	unsigned long clkctrl_emi;
+	unsigned long clkctrl_frac;
+	int div = 1;
+	unsigned long root_rate, cur_emi_div, cur_emi_frac;
+	struct clk *target_parent_p = &ref_xtal_clk;
+
+	if (rate < ref_xtal_get_rate(&ref_xtal_clk))
+		return -EINVAL;
+
+	if (!mxs_ram_funcs_sz)
+		goto out;
+
+	sc_data.cur_freq = (clk->get_rate(clk)) / 1000 / 1000;
+	sc_data.new_freq = rate / 1000 / 1000;
+
+	if (sc_data.cur_freq == sc_data.new_freq)
+		goto out;
+
+	if (rate != ref_xtal_get_rate(&ref_xtal_clk)) {
+		target_parent_p = &ref_emi_clk;
+		pll_enable(&pll_clk);
+
+		root_rate = pll_clk.get_rate(&pll_clk);

 		for (clkctrl_emi = div; clkctrl_emi < 0x3f;
 					clkctrl_emi += div) {
@@ -899,32 +1002,51 @@ static int emi_set_rate(struct clk *clk, unsigned long rate)
 		pr_debug("%s: clkctrl_emi %ld, clkctrl_frac %ld\n",
 			__func__, clkctrl_emi, clkctrl_frac);

-		memcpy(scale, mxs_ram_freq_scale, mxs_ram_funcs_sz);
-
 		sc_data.emi_div = clkctrl_emi;
 		sc_data.frac_div = clkctrl_frac;
-		sc_data.cur_freq = (clk->get_rate(clk)) / 1000 / 1000;
-		sc_data.new_freq = rate / 1000 / 1000;
+	}
+
+
+	cur_emi_div = ((__raw_readl(CLKCTRL_BASE_ADDR+HW_CLKCTRL_EMI) &
+		BM_CLKCTRL_EMI_DIV_EMI) >> BP_CLKCTRL_EMI_DIV_EMI);
+	cur_emi_frac = ((__raw_readl(CLKCTRL_BASE_ADDR+HW_CLKCTRL_FRAC) &
+		BM_CLKCTRL_EMI_DIV_EMI) >> BP_CLKCTRL_FRAC_EMIFRAC);
+
+	if ((cur_emi_div == sc_data.emi_div) &&
+		(cur_emi_frac == sc_data.frac_div))
+		goto out;
+
+
+	{
+		unsigned long iram_phy;
+		int (*scale)(struct mxs_emi_scaling_data *) =
+			iram_alloc(mxs_ram_funcs_sz, &iram_phy);
+
+		if (NULL == scale) {
+			pr_err("%s Not enough iram\n", __func__);
+			return -ENOMEM;
+		}
+
+		memcpy(scale, mxs_ram_freq_scale, mxs_ram_funcs_sz);

 		local_irq_disable();
 		local_fiq_disable();
-		iram_free(iram_phy, 0x1000);

 		scale(&sc_data);

+		iram_free(iram_phy, mxs_ram_funcs_sz);
+
 		local_fiq_enable();
 		local_irq_enable();
-
-		for (i = 10000; i; i--)
-			if (!clk_is_busy(clk))
-				break;
-
-		if (!i) {
-			printk(KERN_ERR "couldn't set up EMI divisor\n");
-			ret = -ETIMEDOUT;
-			goto out;
-		}
 	}
+
+	/* this code is for keeping track of ref counts.
+	 * and disabling previous parent if necessary
+	 * actual clkseq changes have already
+	 * been made.
+	 */
+	clk_set_parent(clk, target_parent_p);
+
 out:
 	return ret;
 }
@@ -952,36 +1074,39 @@ static unsigned long ssp_get_rate(struct clk *clk);
 static int ssp_set_rate(struct clk *clk, unsigned long rate)
 {
 	int ret = -EINVAL;
-	int div = (clk_get_rate(clk->parent) + rate - 1) / rate;
-	u32 reg_frac;
-	const int mask = 0x1FF;
-	int try = 10;
-	int i = -1;
+	u32 reg, div;

-	if (div == 0 || div > mask)
+
+	/* because SSP_CLK is used by more than one SSP peripheral,
+	 * we only allow the clock to be changed if no driver is currently
+	 * using the clock.
+	 */
+	if (clk->ref & CLK_EN_MASK)
+		return -EBUSY;
+
+	/* if the desired clock can be sourced from ref_xtal,
+	 * use ref_xtal to save power
+	 */
+	if ((rate <= ref_xtal_get_rate(&ref_xtal_clk)) &&
+		((ref_xtal_get_rate(&ref_xtal_clk) % rate) == 0))
+		clk_set_parent(clk, &ref_xtal_clk);
+	else
+		clk_set_parent(clk, &ref_io_clk);
+
+	if (rate > PLL_ENABLED_MAX_CLK_SSP)
+		rate = PLL_ENABLED_MAX_CLK_SSP;
+
+	div = (clk_get_rate(clk->parent) + rate - 1) / rate;
+
+	if (div == 0 || div > BM_CLKCTRL_SSP_DIV)
 		goto out;

-	reg_frac = __raw_readl(clk->scale_reg);
-	reg_frac &= ~(mask << clk->scale_bits);
-
-	while (try--) {
-		__raw_writel(reg_frac | (div << clk->scale_bits),
-				clk->scale_reg);
-
-		if (clk->busy_reg) {
-			for (i = 10000; i; i--)
-				if (!clk_is_busy(clk))
-					break;
-		}
-		if (i)
-			break;
-	}
-
-	if (!i)
-		ret = -ETIMEDOUT;
-	else
-		ret = 0;
+	reg = __raw_readl(clk->scale_reg);
+	reg &= ~(BM_CLKCTRL_SSP_DIV | BM_CLKCTRL_SSP_DIV_FRAC_EN);
+	reg |= div << clk->scale_bits;
+	__raw_writel(reg, clk->scale_reg);

+	ret = clk_busy_wait(clk);
 out:
 	if (ret != 0)
 		printk(KERN_ERR "%s: error %d\n", __func__, ret);
@@ -1008,6 +1133,26 @@ static int ssp_set_parent(struct clk *clk, struct clk *parent)
 	return ret;
 }

+/* handle peripheral clocks whose optimal parent dependent on
+ * system parameters such as cpu_clk rate.  For now, this optimization
+ * only occurs to the peripheral clock when it's not in use to avoid
+ * handling more complex system clock coordination issues.
+ */
+static int ssp_set_sys_dependent_parent(struct clk *clk)
+{
+	if ((clk->ref & CLK_EN_MASK) == 0) {
+		if (clk_get_rate(&cpu_clk) > ref_xtal_get_rate(&ref_xtal_clk)) {
+			clk_set_parent(clk, &ref_io_clk);
+			clk_set_rate(clk, PLL_ENABLED_MAX_CLK_SSP);
+		} else {
+			clk_set_parent(clk, &ref_xtal_clk);
+			clk_set_rate(clk, ref_xtal_get_rate(&ref_xtal_clk));
+		}
+	}
+
+	return 0;
+}
+
 static struct clk ssp_clk = {
 	 .parent = &ref_io_clk,
 	 .get_rate = ssp_get_rate,
@@ -1023,6 +1168,7 @@ static struct clk ssp_clk = {
 	 .bypass_bits = 3,
 	 .set_rate = ssp_set_rate,
 	 .set_parent = ssp_set_parent,
+	 .set_sys_dependent_parent = ssp_set_sys_dependent_parent,
 };

 static unsigned long ssp_get_rate(struct clk *clk)
@@ -1046,35 +1192,31 @@ static unsigned long gpmi_get_rate(struct clk *clk)
 static int gpmi_set_rate(struct clk *clk, unsigned long rate)
 {
 	int ret = -EINVAL;
-	int div = (clk_get_rate(clk->parent) + rate - 1) / rate;
-	u32 reg_frac;
-	const int mask = (BM_CLKCTRL_GPMI_DIV >> clk->scale_bits);
-	int try = 10;
-	int i = -1;
+	u32 reg, div;

-	if (div == 0 || div > mask)
+	/* if the desired clock can be sourced from ref_xtal,
+	 * use ref_xtal to save power
+	 */
+	if ((rate <= ref_xtal_get_rate(&ref_xtal_clk)) &&
+		((ref_xtal_get_rate(&ref_xtal_clk) % rate) == 0))
+		clk_set_parent(clk, &ref_xtal_clk);
+	else
+		clk_set_parent(clk, &ref_io_clk);
+
+	if (rate > PLL_ENABLED_MAX_CLK_SSP)
+		rate = PLL_ENABLED_MAX_CLK_GPMI;
+
+	div = (clk_get_rate(clk->parent) + rate - 1) / rate;
+
+	if (div == 0 || div > BM_CLKCTRL_GPMI_DIV)
 		goto out;

-	reg_frac  = __raw_readl(clk->scale_reg);
-	reg_frac &= ~(mask << clk->scale_bits);
+	reg = __raw_readl(clk->scale_reg);
+	reg &= ~(BM_CLKCTRL_GPMI_DIV | BM_CLKCTRL_GPMI_DIV_FRAC_EN);
+	reg |= div << clk->scale_bits;
+	__raw_writel(reg, clk->scale_reg);

-	while (try--) {
-		__raw_writel(reg_frac | (div << clk->scale_bits),
-								clk->scale_reg);
-
-		if (clk->busy_reg) {
-			for (i = 10000; i; i--)
-				if (!clk_is_busy(clk))
-					break;
-		}
-		if (i)
-			break;
-	}
-
-	if (!i)
-		ret = -ETIMEDOUT;
-	else
-		ret = 0;
+	ret = clk_busy_wait(clk);

 out:
 	if (ret != 0)
@@ -1185,18 +1327,6 @@ static struct clk tv27M_clk = {
 };

 static struct clk_lookup onchip_clocks[] = {
-	{
-	 .con_id = "xtal.0",
-	 .clk = &xtal_clk[0],
-	 },
-	{
-	 .con_id = "xtal.1",
-	 .clk = &xtal_clk[1],
-	 },
-	{
-	 .con_id = "xtal.2",
-	 .clk = &xtal_clk[2],
-	 },
 	{
 	 .con_id = "pll.0",
 	 .clk = &pll_clk,
@@ -1225,9 +1355,13 @@ static struct clk_lookup onchip_clocks[] = {
 	 .con_id = "lcdif",
 	 .clk = &lcdif_clk,
 	 },
+	{
+	 .con_id = "xtal_clock32k",
+	 .clk = &xtal_clock32k_clk,
+	 },
 	{
 	 .con_id = "rtc",
-	 .clk = &rtc_clk,
+	 .clk = &rtc32k_clk,
 	 },
 	{
 	 .con_id = "cpu",
@@ -1299,6 +1433,47 @@ static struct clk_lookup onchip_clocks[] = {
 	},
 };

+/* for debugging */
+#ifdef DEBUG
+static void print_ref_counts(void)
+{
+
+	printk(KERN_INFO "pll_clk ref count: %i\n",
+		pll_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "ref_cpu_clk ref count: %i\n",
+		ref_cpu_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "ref_emi_clk ref count: %i\n",
+		ref_emi_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "ref_pix_clk ref count: %i\n",
+		ref_pix_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "lcdif_clk ref count: %i\n",
+		lcdif_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "ref_io_clk ref count: %i\n",
+		ref_io_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "ssp_clk ref count: %i\n",
+		ssp_clk.ref & CLK_EN_MASK);
+
+	printk(KERN_INFO "gpmi_clk ref count: %i\n",
+		gpmi_clk.ref & CLK_EN_MASK);
+
+}
+#endif
+
+void clk_set_hbus_autoslow_bits(u16 mask)
+{
+	u32 reg;
+
+	reg = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_HBUS);
+	reg &= 0xFFFF;
+	reg |= mask << 16;
+	__raw_writel(reg, CLKCTRL_BASE_ADDR + HW_CLKCTRL_HBUS);
+}

 static void mx23_clock_scan(void)
 {
@@ -1312,16 +1487,17 @@ static void mx23_clock_scan(void)
 		ssp_clk.parent = &ref_xtal_clk;
 	if (reg & BM_CLKCTRL_CLKSEQ_BYPASS_GPMI)
 		gpmi_clk.parent = &ref_xtal_clk;
-};

+	reg = __raw_readl(RTC_BASE_ADDR + HW_RTC_PERSISTENT0);
+	if (!(reg & BM_RTC_PERSISTENT0_CLOCKSOURCE))
+		rtc32k_clk.parent = &ref_xtal_clk;
+};

 void __init mx23_set_input_clk(unsigned long xtal0,
 			       unsigned long xtal1,
 			       unsigned long xtal2, unsigned long enet)
 {
-	xtal_clk_rate[0] = xtal0;
-	xtal_clk_rate[1] = xtal1;
-	xtal_clk_rate[2] = xtal2;
+
 }

 void __init mx23_clock_init(void)
--- a/arch/arm/mach-mx28/clock.c
+++ b/arch/arm/mach-mx28/clock.c
@@ -1652,6 +1652,16 @@ static struct clk_lookup onchip_clocks[] = {
 	}
 };

+void clk_set_hbus_autoslow_bits(u16 mask)
+{
+	u32 reg;
+
+	reg = __raw_readl(CLKCTRL_BASE_ADDR + HW_CLKCTRL_HBUS);
+	reg &= 0xFFFF;
+	reg |= mask << 16;
+	__raw_writel(reg, CLKCTRL_BASE_ADDR + HW_CLKCTRL_HBUS);
+}
+
 static void mx28_clock_scan(void)
 {
 	unsigned long reg;
--- a/arch/arm/plat-mxs/clock.c
+++ b/arch/arm/plat-mxs/clock.c
@@ -110,6 +110,10 @@ int clk_enable(struct clk *clk)

 	spin_lock_irqsave(&clockfw_lock, flags);
 	pre_usage = (clk->ref & CLK_EN_MASK);
+
+	if (clk->set_sys_dependent_parent)
+		clk->set_sys_dependent_parent(clk);
+
 	ret = __clk_enable(clk);
 	spin_unlock_irqrestore(&clockfw_lock, flags);
 	if ((clk->flags & CPU_FREQ_TRIG_UPDATE)
--- a/arch/arm/plat-mxs/include/mach/clock.h
+++ b/arch/arm/plat-mxs/include/mach/clock.h
@@ -72,12 +72,22 @@ struct clk {
 	void (*disable) (struct clk *);
 	/* Function ptr to set the parent clock of the clock. */
 	int (*set_parent) (struct clk *, struct clk *);
+
+	/* Function ptr to change the parent clock depending
+	 * the system configuration at that time.  Will only
+	 * change the parent clock if the ref count is 0 (the clock
+	 * is not being used)
+	 */
+	int (*set_sys_dependent_parent) (struct clk *);
+
 };

 int clk_get_usecount(struct clk *clk);
 extern int clk_register(struct clk_lookup *lookup);
 extern void clk_unregister(struct clk_lookup *lookup);

+void clk_set_hbus_autoslow_bits(u16 mask);
+
 struct mxs_emi_scaling_data {
 	u32 emi_div;
 	u32 frac_div;