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ARM: uniphier: compute SSCPLL values more precisely

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Use DIV_ROUND_CLOSEST().  To make the JK value even more precise,
I used a bigger coefficient, then divide it by 512.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada 2017-12-06 14:16:33 +09:00
parent c30c44e799
commit f2ce50b2d0
1 changed files with 4 additions and 2 deletions
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6
arch/arm/mach-uniphier/clk/pll-base-ld20.c
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@ -7,6 +7,7 @@
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/sizes.h>
@ -41,13 +42,14 @@ int uniphier_ld20_sscpll_init(unsigned long reg_base, unsigned int freq,
if (freq != UNIPHIER_PLL_FREQ_DEFAULT) {
tmp = readl(base); /* SSCPLLCTRL */
tmp &= ~SC_PLLCTRL_SSC_DK_MASK;
tmp |= (487 * freq * ssc_rate / divn / 512) &
tmp |= DIV_ROUND_CLOSEST(487UL * freq * ssc_rate, divn * 512) &
SC_PLLCTRL_SSC_DK_MASK;
writel(tmp, base);
tmp = readl(base + 4);
tmp &= ~SC_PLLCTRL2_SSC_JK_MASK;
tmp |= (41859 * freq / divn) & SC_PLLCTRL2_SSC_JK_MASK;
tmp |= DIV_ROUND_CLOSEST(21431887UL * freq, divn * 512) &
SC_PLLCTRL2_SSC_JK_MASK;
writel(tmp, base + 4);
udelay(50);