clk: pxa: transfer CPU clock setting from pxa2xx-cpufreq

This is the initial stage to transfer the pxa25x and pxa27x CPU clocks
handling from cpufreq to the clock API. More precisely, the clocks
transferred are :
 - cpll : core pll, known also as the CPU core turbo frequency
 - core : core, known also as the CPU actual frequency, being either the
          CPU core turbo frequency or the CPU core run frequency

This transfer is a prequel to shrink the code in pxa2xx-cpufreq.c, so
that it can become, at least in devicetree builds, the casual cpufreq-dt
driver.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/pxa/clk-pxa.c

@@ -18,6 +18,26 @@
 #include <dt-bindings/clock/pxa-clock.h>
 #include "clk-pxa.h"
 
+#define KHz 1000
+#define MHz (1000 * 1000)
+
+#define MDREFR_K0DB4	(1 << 29)	/* SDCLK0 Divide by 4 Control/Status */
+#define MDREFR_K2FREE	(1 << 25)	/* SDRAM Free-Running Control */
+#define MDREFR_K1FREE	(1 << 24)	/* SDRAM Free-Running Control */
+#define MDREFR_K0FREE	(1 << 23)	/* SDRAM Free-Running Control */
+#define MDREFR_SLFRSH	(1 << 22)	/* SDRAM Self-Refresh Control/Status */
+#define MDREFR_APD	(1 << 20)	/* SDRAM/SSRAM Auto-Power-Down Enable */
+#define MDREFR_K2DB2	(1 << 19)	/* SDCLK2 Divide by 2 Control/Status */
+#define MDREFR_K2RUN	(1 << 18)	/* SDCLK2 Run Control/Status */
+#define MDREFR_K1DB2	(1 << 17)	/* SDCLK1 Divide by 2 Control/Status */
+#define MDREFR_K1RUN	(1 << 16)	/* SDCLK1 Run Control/Status */
+#define MDREFR_E1PIN	(1 << 15)	/* SDCKE1 Level Control/Status */
+#define MDREFR_K0DB2	(1 << 14)	/* SDCLK0 Divide by 2 Control/Status */
+#define MDREFR_K0RUN	(1 << 13)	/* SDCLK0 Run Control/Status */
+#define MDREFR_E0PIN	(1 << 12)	/* SDCKE0 Level Control/Status */
+#define MDREFR_DB2_MASK	(MDREFR_K2DB2 | MDREFR_K1DB2)
+#define MDREFR_DRI_MASK	0xFFF
+
 DEFINE_SPINLOCK(lock);
 
 static struct clk *pxa_clocks[CLK_MAX];
@@ -106,3 +126,122 @@ void __init clk_pxa_dt_common_init(struct device_node *np)
 {
 	of_clk_add_provider(np, of_clk_src_onecell_get, &onecell_data);
 }
+
+void pxa2xx_core_turbo_switch(bool on)
+{
+	unsigned long flags;
+	unsigned int unused, clkcfg;
+
+	local_irq_save(flags);
+
+	asm("mrc p14, 0, %0, c6, c0, 0" : "=r" (clkcfg));
+	clkcfg &= ~CLKCFG_TURBO & ~CLKCFG_HALFTURBO;
+	if (on)
+		clkcfg |= CLKCFG_TURBO;
+	clkcfg |= CLKCFG_FCS;
+
+	asm volatile(
+	"	b	2f\n"
+	"	.align	5\n"
+	"1:	mcr	p14, 0, %1, c6, c0, 0\n"
+	"	b	3f\n"
+	"2:	b	1b\n"
+	"3:	nop\n"
+		: "=&r" (unused)
+		: "r" (clkcfg)
+		: );
+
+	local_irq_restore(flags);
+}
+
+void pxa2xx_cpll_change(struct pxa2xx_freq *freq,
+			u32 (*mdrefr_dri)(unsigned int), u32 *mdrefr, u32 *cccr)
+{
+	unsigned int clkcfg = freq->clkcfg;
+	unsigned int unused, preset_mdrefr, postset_mdrefr;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	/* Calculate the next MDREFR.  If we're slowing down the SDRAM clock
+	 * we need to preset the smaller DRI before the change.	 If we're
+	 * speeding up we need to set the larger DRI value after the change.
+	 */
+	preset_mdrefr = postset_mdrefr = readl(mdrefr);
+	if ((preset_mdrefr & MDREFR_DRI_MASK) > mdrefr_dri(freq->membus_khz)) {
+		preset_mdrefr = (preset_mdrefr & ~MDREFR_DRI_MASK);
+		preset_mdrefr |= mdrefr_dri(freq->membus_khz);
+	}
+	postset_mdrefr =
+		(postset_mdrefr & ~MDREFR_DRI_MASK) |
+		mdrefr_dri(freq->membus_khz);
+
+	/* If we're dividing the memory clock by two for the SDRAM clock, this
+	 * must be set prior to the change.  Clearing the divide must be done
+	 * after the change.
+	 */
+	if (freq->div2) {
+		preset_mdrefr  |= MDREFR_DB2_MASK;
+		postset_mdrefr |= MDREFR_DB2_MASK;
+	} else {
+		postset_mdrefr &= ~MDREFR_DB2_MASK;
+	}
+
+	/* Set new the CCCR and prepare CLKCFG */
+	writel(freq->cccr, cccr);
+
+	asm volatile(
+	"	ldr	r4, [%1]\n"
+	"	b	2f\n"
+	"	.align	5\n"
+	"1:	str	%3, [%1]		/* preset the MDREFR */\n"
+	"	mcr	p14, 0, %2, c6, c0, 0	/* set CLKCFG[FCS] */\n"
+	"	str	%4, [%1]		/* postset the MDREFR */\n"
+	"	b	3f\n"
+	"2:	b	1b\n"
+	"3:	nop\n"
+	     : "=&r" (unused)
+	     : "r" (mdrefr), "r" (clkcfg), "r" (preset_mdrefr),
+	       "r" (postset_mdrefr)
+	     : "r4", "r5");
+
+	local_irq_restore(flags);
+}
+
+int pxa2xx_determine_rate(struct clk_rate_request *req,
+			  struct pxa2xx_freq *freqs, int nb_freqs)
+{
+	int i, closest_below = -1, closest_above = -1, ret = 0;
+	unsigned long rate;
+
+	for (i = 0; i < nb_freqs; i++) {
+		rate = freqs[i].cpll;
+		if (rate == req->rate)
+			break;
+		if (rate < req->min_rate)
+			continue;
+		if (rate > req->max_rate)
+			continue;
+		if (rate <= req->rate)
+			closest_below = i;
+		if ((rate >= req->rate) && (closest_above == -1))
+			closest_above = i;
+	}
+
+	req->best_parent_hw = NULL;
+
+	if (i < nb_freqs)
+		ret = 0;
+	else if (closest_below >= 0)
+		rate = freqs[closest_below].cpll;
+	else if (closest_above >= 0)
+		rate = freqs[closest_above].cpll;
+	else
+		ret = -EINVAL;
+
+	pr_debug("%s(rate=%lu) rate=%lu: %d\n", __func__, req->rate, rate, ret);
+	if (!rate)
+		req->rate = rate;
+
+	return ret;
+}