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 */
omap36xx_pwrdn_clk_enable_with_hsdiv_restore(struct clk * clk)42 static 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
67 const 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