From 11cca264ff57ad0b234bd1cd2c9a2366b967feb7 Mon Sep 17 00:00:00 2001
From: Michael Sevakis <jethead71@rockbox.org>
Date: Fri, 23 Apr 2010 15:32:50 +0000
Subject: i.MX31/Gigabeat S: Implement frequency and voltage scaling-- 1.6V for
 528MHz, and 1.35V for 264MHz and 132MHz. Keep DPTC overdrive ( > 400MHz)
 voltage scaling off for now because of uncertainties. Simplify the (working)
 mess later.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25699 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/arm/imx31/ccm-imx31.c | 62 ++++++++++++++++++++++++++---------
 1 file changed, 47 insertions(+), 15 deletions(-)

(limited to 'firmware/target/arm/imx31/ccm-imx31.c')

diff --git a/firmware/target/arm/imx31/ccm-imx31.c b/firmware/target/arm/imx31/ccm-imx31.c
index 0d166e5dbf..2cf2080cf1 100644
--- a/firmware/target/arm/imx31/ccm-imx31.c
+++ b/firmware/target/arm/imx31/ccm-imx31.c
@@ -24,7 +24,8 @@
 #include "cpu.h"
 #include "ccm-imx31.h"
 
-unsigned int ccm_get_src_pll(void)
+/* Return the current source pll for MCU */
+enum IMX31_PLLS ccm_get_src_pll(void)
 {
     return (CCM_PMCR0 & 0xC0000000) == 0 ? PLL_SERIAL : PLL_MCU;
 }
@@ -45,8 +46,21 @@ void ccm_module_clock_gating(enum IMX31_CG_LIST cg, enum IMX31_CG_MODES mode)
     imx31_regmod32(reg, mode << shift, mask);
 }
 
+/* Decode PLL output frequency from register value */
+unsigned int ccm_calc_pll_rate(unsigned int infreq, unsigned long regval)
+{
+    uint32_t mfn = regval & 0x3ff;
+    uint32_t pd  = ((regval >> 26) & 0xf) + 1;
+    uint32_t mfd = ((regval >> 16) & 0x3ff) + 1;
+    uint32_t mfi = (regval >> 10) & 0xf;
+
+    mfi = mfi <= 5 ? 5 : mfi;
+
+    return 2ull*infreq*(mfi * mfd + mfn) / (mfd * pd);
+}
+
 /* Get the PLL reference clock frequency in HZ */
-unsigned int ccm_get_pll_ref_clk(void)
+unsigned int ccm_get_pll_ref_clk_rate(void)
 {
     if ((CCM_CCMR & (3 << 1)) == (1 << 1))
         return CONFIG_CKIL_FREQ * 1024;
@@ -55,41 +69,59 @@ unsigned int ccm_get_pll_ref_clk(void)
 }
 
 /* Return PLL frequency in HZ */
-unsigned int ccm_get_pll(enum IMX31_PLLS pll)
+unsigned int ccm_get_pll_rate(enum IMX31_PLLS pll)
 {
-    uint32_t infreq = ccm_get_pll_ref_clk();
-    uint32_t reg = (&CCM_MPCTL)[pll];
-    uint32_t mfn = reg & 0x3ff;
-    uint32_t pd  = ((reg >> 26) & 0xf) + 1;
-    uint64_t mfd = ((reg >> 16) & 0x3ff) + 1;
-    uint32_t mfi = (reg >> 10) & 0xf;
+    return ccm_calc_pll_rate(ccm_get_pll_ref_clk_rate(), (&CCM_MPCTL)[pll]);
+}
 
-    mfi = mfi <= 5 ? 5 : mfi;
+unsigned int ccm_get_mcu_clk(void)
+{
+    unsigned int pllnum = ccm_get_src_pll();
+    unsigned int fpll = ccm_get_pll_rate(pllnum);
+    unsigned int mcu_podf = (CCM_PDR0 & 0x7) + 1;
 
-    return 2*infreq*(mfi * mfd + mfn) / (mfd * pd);
+    return fpll / mcu_podf;
 }
 
 unsigned int ccm_get_ipg_clk(void)
 {
     unsigned int pllnum = ccm_get_src_pll();
-    unsigned int pll = ccm_get_pll(pllnum);
+    unsigned int fpll = ccm_get_pll_rate(pllnum);
     uint32_t reg = CCM_PDR0;
     unsigned int max_pdf = ((reg >> 3) & 0x7) + 1;
     unsigned int ipg_pdf = ((reg >> 6) & 0x3) + 1;
 
-    return pll / (max_pdf * ipg_pdf);
+    return fpll / (max_pdf * ipg_pdf);
 }
 
 unsigned int ccm_get_ahb_clk(void)
 {
     unsigned int pllnum = ccm_get_src_pll();
-    unsigned int pll = ccm_get_pll(pllnum);
+    unsigned int fpll = ccm_get_pll_rate(pllnum);
     unsigned int max_pdf = ((CCM_PDR0 >> 3) & 0x7) + 1;
 
-    return pll / max_pdf;
+    return fpll / max_pdf;
 }
 
 unsigned int ccm_get_ata_clk(void)
 {
     return ccm_get_ipg_clk();
 }
+
+/* Write new values to the current PLL and post-dividers */
+void ccm_set_mcupll_and_pdr(unsigned long pllctl, unsigned long pdr)
+{
+    unsigned int pll = ccm_get_src_pll();
+    volatile unsigned long *pllreg = &(&CCM_MPCTL)[pll];
+    unsigned long fref = ccm_get_pll_ref_clk_rate();
+    unsigned long curfreq = ccm_calc_pll_rate(fref, *pllreg);
+    unsigned long newfreq = ccm_calc_pll_rate(fref, pllctl);
+
+    if (newfreq > curfreq)
+        CCM_PDR0 = pdr;
+
+    *pllreg = pllctl;
+
+    if (newfreq <= curfreq)
+        CCM_PDR0 = pdr;
+}
-- 
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