OMAP3 clock: introduce DPLL4 Jtype

DPLL4 for 3630 introduces a changed block called j type dpll, requiring
special divisor bits and additional reg fields. To allow for silicons to
use this, this is introduced as a flag and is enabled for 3630 silicon.
OMAP4 also has j type dpll for usb.

Tested with 3630 ZOOM3 and OMAP3430 ZOOM2

Signed-off-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Vishwanath BS <Vishwanath.bs@ti.com>
[paul@pwsan.com: added some comments; updated copyrights and credits; fixed
 some style issues]
Signed-off-by: Paul Walmsley <paul@pwsan.com>

1 files changed, 63 insertions, 4 deletions

diff --git a/arch/arm/mach-omap2/dpll3xxx.c b/arch/arm/mach-omap2/dpll3xxx.c
index 68268cd89e05..417c3caa05db 100644
--- a/arch/arm/mach-omap2/dpll3xxx.c
+++ b/arch/arm/mach-omap2/dpll3xxx.c
@@ -1,11 +1,14 @@
 /*
  * OMAP3/4 - specific DPLL control functions
  *
- * Copyright (C) 2009 Texas Instruments, Inc.
- * Copyright (C) 2009 Nokia Corporation
+ * Copyright (C) 2009-2010 Texas Instruments, Inc.
+ * Copyright (C) 2009-2010 Nokia Corporation
  *
  * Written by Paul Walmsley
- * Testing and integration fixes by Jouni Högander
+ * Testing and integration fixes by Jouni Högander
+ *
+ * 36xx support added by Vishwanath BS, Richard Woodruff, and Nishanth
+ * Menon
  *
  * Parts of this code are based on code written by
  * Richard Woodruff, Tony Lindgren, Tuukka Tikkanen, Karthik Dasu
@@ -225,6 +228,47 @@ static int _omap3_noncore_dpll_stop(struct clk *clk)
         return 0;
 }
 
+/**
+ * lookup_dco_sddiv -  Set j-type DPLL4 compensation variables
+ * @clk: pointer to a DPLL struct clk
+ * @dco: digital control oscillator selector
+ * @sd_div: target sigma-delta divider
+ * @m: DPLL multiplier to set
+ * @n: DPLL divider to set
+ *
+ * See 36xx TRM section 3.5.3.3.3.2 "Type B DPLL (Low-Jitter)"
+ *
+ * XXX This code is not needed for 3430/AM35xx; can it be optimized
+ * out in non-multi-OMAP builds for those chips?
+ */
+static void lookup_dco_sddiv(struct clk *clk, u8 *dco, u8 *sd_div, u16 m,
+                             u8 n)
+{
+        unsigned long fint, clkinp, sd; /* watch out for overflow */
+        int mod1, mod2;
+
+        clkinp = clk->parent->rate;
+        fint = (clkinp / n) * m;
+
+        if (fint < 1000000000)
+                *dco = 2;
+        else
+                *dco = 4;
+        /*
+         * target sigma-delta to near 250MHz
+         * sd = ceil[(m/(n+1)) * (clkinp_MHz / 250)]
+         */
+        clkinp /= 100000; /* shift from MHz to 10*Hz for 38.4 and 19.2 */
+        mod1 = (clkinp * m) % (250 * n);
+        sd = (clkinp * m) / (250 * n);
+        mod2 = sd % 10;
+        sd /= 10;
+
+        if (mod1 || mod2)
+                sd++;
+        *sd_div = sd;
+}
+
 /*
  * _omap3_noncore_dpll_program - set non-core DPLL M,N values directly
  * @clk: struct clk * of DPLL to set
@@ -259,6 +303,21 @@ static int omap3_noncore_dpll_program(struct clk *clk, u16 m, u8 n, u16 freqsel)
         v &= ~(dd->mult_mask | dd->div1_mask);
         v |= m << __ffs(dd->mult_mask);
         v |= (n - 1) << __ffs(dd->div1_mask);
+
+        /*
+         * XXX This code is not needed for 3430/AM35XX; can it be optimized
+         * out in non-multi-OMAP builds for those chips?
+         */
+        if ((dd->flags & DPLL_J_TYPE) && !(dd->flags & DPLL_NO_DCO_SEL)) {
+                u8 dco, sd_div;
+                lookup_dco_sddiv(clk, &dco, &sd_div, m, n);
+                /* XXX This probably will need revision for OMAP4 */
+                v &= ~(OMAP3630_PERIPH_DPLL_DCO_SEL_MASK
+                        | OMAP3630_PERIPH_DPLL_SD_DIV_MASK);
+                v |= dco << __ffs(OMAP3630_PERIPH_DPLL_DCO_SEL_MASK);
+                v |= sd_div << __ffs(OMAP3630_PERIPH_DPLL_SD_DIV_MASK);
+        }
+
         __raw_writel(v, dd->mult_div1_reg);
 
         /* We let the clock framework set the other output dividers later */
@@ -536,7 +595,7 @@ unsigned long omap3_clkoutx2_recalc(struct clk *clk)
 
         v = __raw_readl(dd->control_reg) & dd->enable_mask;
         v >>= __ffs(dd->enable_mask);
-        if (v != OMAP3XXX_EN_DPLL_LOCKED)
+        if ((v != OMAP3XXX_EN_DPLL_LOCKED) || (dd->flags & DPLL_J_TYPE))
                 rate = clk->parent->rate;
         else
                 rate = clk->parent->rate * 2;