From cf5db5477d8d43f02f4511f3835ab4bec0dcc27c Mon Sep 17 00:00:00 2001
From: Richard Watts <rrw@kynesim.co.uk>
Date: Mon, 20 Feb 2012 17:58:26 +0000
Subject: [PATCH] Fix sprz319 erratum 2.1

There is an erratum in DM3730 which results in the
EHCI USB PLL (DPLL5) not updating sufficiently frequently; this
leads to USB PHY clock drift and once the clock has drifted far
enough, the PHY's ULPI interface stops responding and USB
drops out. This is manifested on a Beagle xM by having the attached
SMSC9514 report 'Cannot enable port 2. Maybe the USB cable is bad?'
or similar.

The fix is to carefully adjust your DPLL5 settings so as to
keep the PHY clock as close as possible to 120MHz over the long
term; TI SPRZ319e gives a table of such settings and this patch
applies that table to systems with a 13MHz or a 26MHz clock,
thus fixing the issue (inasfar as it can be fixed) on Beagle xM
and Overo Firestorm.

Signed-off-by: Richard Watts <rrw@kynesim.co.uk>
---
 arch/arm/mach-omap2/clkt_clksel.c    |   15 ++++++++
 arch/arm/mach-omap2/clock.h          |    7 ++++
 arch/arm/mach-omap2/clock3xxx.c      |   65 +++++++++++++++++++++++++++++----
 arch/arm/mach-omap2/clock3xxx.h      |    1 +
 arch/arm/mach-omap2/clock3xxx_data.c |    2 +-
 arch/arm/mach-omap2/dpll3xxx.c       |    2 +-
 6 files changed, 82 insertions(+), 10 deletions(-)

diff --git a/arch/arm/mach-omap2/clkt_clksel.c b/arch/arm/mach-omap2/clkt_clksel.c
index e25364d..e378fe7 100644
--- a/arch/arm/mach-omap2/clkt_clksel.c
+++ b/arch/arm/mach-omap2/clkt_clksel.c
@@ -460,6 +460,21 @@ int omap2_clksel_set_rate(struct clk *clk, unsigned long rate)
 	return 0;
 }
 
+int omap2_clksel_force_divisor(struct clk *clk, int new_div)
+{
+	u32 field_val;
+
+	field_val = _divisor_to_clksel(clk, new_div);
+	if (field_val == ~0)
+		return -EINVAL;
+
+	_write_clksel_reg(clk, field_val);
+
+	clk->rate = clk->parent->rate / new_div;
+
+	return 0;
+}
+
 /*
  * Clksel parent setting function - not passed in struct clk function
  * pointer - instead, the OMAP clock code currently assumes that any
diff --git a/arch/arm/mach-omap2/clock.h b/arch/arm/mach-omap2/clock.h
index 8bad1c6..ac3d367 100644
--- a/arch/arm/mach-omap2/clock.h
+++ b/arch/arm/mach-omap2/clock.h
@@ -61,6 +61,12 @@ void omap3_dpll_allow_idle(struct clk *clk);
 void omap3_dpll_deny_idle(struct clk *clk);
 u32 omap3_dpll_autoidle_read(struct clk *clk);
 int omap3_noncore_dpll_set_rate(struct clk *clk, unsigned long rate);
+#if CONFIG_ARCH_OMAP3
+int omap3_noncore_dpll_program(struct clk *clk, u16 m, u8 n, u16 freqsel);
+/* If you are using this function and not on OMAP3, you are
+ * Doing It Wrong(tm), so there is no stub.
+ */
+#endif
 int omap3_noncore_dpll_enable(struct clk *clk);
 void omap3_noncore_dpll_disable(struct clk *clk);
 int omap4_dpllmx_gatectrl_read(struct clk *clk);
@@ -84,6 +90,7 @@ unsigned long omap2_clksel_recalc(struct clk *clk);
 long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate);
 int omap2_clksel_set_rate(struct clk *clk, unsigned long rate);
 int omap2_clksel_set_parent(struct clk *clk, struct clk *new_parent);
+int omap2_clksel_force_divisor(struct clk *clk, int new_div);
 
 /* clkt_iclk.c public functions */
 extern void omap2_clkt_iclk_allow_idle(struct clk *clk);
diff --git a/arch/arm/mach-omap2/clock3xxx.c b/arch/arm/mach-omap2/clock3xxx.c
index 952c3e0..d5be086 100644
--- a/arch/arm/mach-omap2/clock3xxx.c
+++ b/arch/arm/mach-omap2/clock3xxx.c
@@ -40,6 +40,60 @@
 /* needed by omap3_core_dpll_m2_set_rate() */
 struct clk *sdrc_ick_p, *arm_fck_p;
 
+struct dpll_settings {
+	int rate, m, n, f;
+};
+
+
+static int omap3_dpll5_apply_erratum21(struct clk *clk, struct clk *dpll5_m2)
+{
+	struct clk *sys_clk;
+	int i, rv;
+	static const struct dpll_settings precomputed[] = {
+		/* From DM3730 errata (sprz319e), table 36
+		* +1 is because the values in the table are register values;
+		* dpll_program() will subtract one from what we give it,
+		* so ...
+		*/
+		{ 13000000, 443+1, 5+1, 8 },
+		{ 26000000, 443+1, 11+1, 8 }
+	};
+
+	sys_clk = clk_get(NULL, "sys_ck");
+
+	for (i = 0 ; i < (sizeof(precomputed)/sizeof(struct dpll_settings)) ;
+		++i) {
+		const struct dpll_settings *d = &precomputed[i];
+		if (sys_clk->rate == d->rate) {
+			rv =  omap3_noncore_dpll_program(clk, d->m , d->n, 0);
+			if (rv)
+				return 1;
+			rv =  omap2_clksel_force_divisor(dpll5_m2 , d->f);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+int omap3_dpll5_set_rate(struct clk *clk, unsigned long rate)
+{
+	struct clk *dpll5_m2;
+	int rv;
+	dpll5_m2 = clk_get(NULL, "dpll5_m2_ck");
+
+	if (cpu_is_omap3630() && rate == DPLL5_FREQ_FOR_USBHOST &&
+		omap3_dpll5_apply_erratum21(clk, dpll5_m2)) {
+		return 1;
+	}
+	rv = omap3_noncore_dpll_set_rate(clk, rate);
+	if (rv)
+		goto out;
+	rv = clk_set_rate(dpll5_m2, rate);
+
+out:
+	return rv;
+}
+
 int omap3_dpll4_set_rate(struct clk *clk, unsigned long rate)
 {
 	/*
@@ -59,19 +113,14 @@ int omap3_dpll4_set_rate(struct clk *clk, unsigned long rate)
 void __init omap3_clk_lock_dpll5(void)
 {
 	struct clk *dpll5_clk;
-	struct clk *dpll5_m2_clk;
 
 	dpll5_clk = clk_get(NULL, "dpll5_ck");
 	clk_set_rate(dpll5_clk, DPLL5_FREQ_FOR_USBHOST);
-	clk_enable(dpll5_clk);
 
-	/* Program dpll5_m2_clk divider for no division */
-	dpll5_m2_clk = clk_get(NULL, "dpll5_m2_ck");
-	clk_enable(dpll5_m2_clk);
-	clk_set_rate(dpll5_m2_clk, DPLL5_FREQ_FOR_USBHOST);
+	/* dpll5_m2_ck is now (grottily!) handled by dpll5_clk's set routine,
+	 * to cope with an erratum on DM3730
+	 */
 
-	clk_disable(dpll5_m2_clk);
-	clk_disable(dpll5_clk);
 	return;
 }
 
diff --git a/arch/arm/mach-omap2/clock3xxx.h b/arch/arm/mach-omap2/clock3xxx.h
index 8bbeeaf..0ede513 100644
--- a/arch/arm/mach-omap2/clock3xxx.h
+++ b/arch/arm/mach-omap2/clock3xxx.h
@@ -10,6 +10,7 @@
 
 int omap3xxx_clk_init(void);
 int omap3_dpll4_set_rate(struct clk *clk, unsigned long rate);
+int omap3_dpll5_set_rate(struct clk *clk, unsigned long rate);
 int omap3_core_dpll_m2_set_rate(struct clk *clk, unsigned long rate);
 void omap3_clk_lock_dpll5(void);
 
diff --git a/arch/arm/mach-omap2/clock3xxx_data.c b/arch/arm/mach-omap2/clock3xxx_data.c
index ffd55b1..dcd7bdc 100644
--- a/arch/arm/mach-omap2/clock3xxx_data.c
+++ b/arch/arm/mach-omap2/clock3xxx_data.c
@@ -942,7 +942,7 @@ static struct clk dpll5_ck = {
 	.parent		= &sys_ck,
 	.dpll_data	= &dpll5_dd,
 	.round_rate	= &omap2_dpll_round_rate,
-	.set_rate	= &omap3_noncore_dpll_set_rate,
+	.set_rate	= &omap3_dpll5_set_rate,
 	.clkdm_name	= "dpll5_clkdm",
 	.recalc		= &omap3_dpll_recalc,
 };
diff --git a/arch/arm/mach-omap2/dpll3xxx.c b/arch/arm/mach-omap2/dpll3xxx.c
index f77022b..1909cd0 100644
--- a/arch/arm/mach-omap2/dpll3xxx.c
+++ b/arch/arm/mach-omap2/dpll3xxx.c
@@ -291,7 +291,7 @@ static void _lookup_sddiv(struct clk *clk, u8 *sd_div, u16 m, u8 n)
  * Program the DPLL with the supplied M, N values, and wait for the DPLL to
  * lock..  Returns -EINVAL upon error, or 0 upon success.
  */
-static int omap3_noncore_dpll_program(struct clk *clk, u16 m, u8 n, u16 freqsel)
+int omap3_noncore_dpll_program(struct clk *clk, u16 m, u8 n, u16 freqsel)
 {
 	struct dpll_data *dd = clk->dpll_data;
 	u8 dco, sd_div;
-- 
1.7.2.5

