1/* 2 * OMAP36xx-specific clkops 3 * 4 * Copyright (C) 2010 Texas Instruments, Inc. 5 * Copyright (C) 2010 Nokia Corporation 6 * 7 * Mike Turquette 8 * Vijaykumar GN 9 * Paul Walmsley 10 * 11 * Parts of this code are based on code written by 12 * Richard Woodruff, Tony Lindgren, Tuukka Tikkanen, Karthik Dasu, 13 * Russell King 14 * 15 * This program is free software; you can redistribute it and/or modify 16 * it under the terms of the GNU General Public License version 2 as 17 * published by the Free Software Foundation. 18 */ 19#undef DEBUG 20 21#include <linux/kernel.h> 22#include <linux/clk.h> 23#include <linux/io.h> 24 25#include <plat/clock.h> 26 27#include "clock.h" 28#include "clock36xx.h" 29 30 31/** 32 * omap36xx_pwrdn_clk_enable_with_hsdiv_restore - enable clocks suffering 33 * from HSDivider PWRDN problem Implements Errata ID: i556. 34 * @clk: DPLL output struct clk 35 * 36 * 3630 only: dpll3_m3_ck, dpll4_m2_ck, dpll4_m3_ck, dpll4_m4_ck, 37 * dpll4_m5_ck & dpll4_m6_ck dividers gets loaded with reset 38 * valueafter their respective PWRDN bits are set. Any dummy write 39 * (Any other value different from the Read value) to the 40 * corresponding CM_CLKSEL register will refresh the dividers. 41 */ 42static int omap36xx_pwrdn_clk_enable_with_hsdiv_restore(struct clk *clk) 43{ 44 u32 dummy_v, orig_v, clksel_shift; 45 int ret; 46 47 /* Clear PWRDN bit of HSDIVIDER */ 48 ret = omap2_dflt_clk_enable(clk); 49 50 /* Restore the dividers */ 51 if (!ret) { 52 clksel_shift = __ffs(clk->parent->clksel_mask); 53 orig_v = __raw_readl(clk->parent->clksel_reg); 54 dummy_v = orig_v; 55 56 /* Write any other value different from the Read value */ 57 dummy_v ^= (1 << clksel_shift); 58 __raw_writel(dummy_v, clk->parent->clksel_reg); 59 60 /* Write the original divider */ 61 __raw_writel(orig_v, clk->parent->clksel_reg); 62 } 63 64 return ret; 65} 66 67const struct clkops clkops_omap36xx_pwrdn_with_hsdiv_wait_restore = { 68 .enable = omap36xx_pwrdn_clk_enable_with_hsdiv_restore, 69 .disable = omap2_dflt_clk_disable, 70 .find_companion = omap2_clk_dflt_find_companion, 71 .find_idlest = omap2_clk_dflt_find_idlest, 72}; 73