1 /*
2 * MSDI IP block reset
3 *
4 * Copyright (C) 2012 Texas Instruments, Inc.
5 * Paul Walmsley
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
19 * 02110-1301 USA
20 *
21 * XXX What about pad muxing?
22 */
23
24 #include <linux/kernel.h>
25 #include <linux/err.h>
26 #include <linux/platform_data/gpio-omap.h>
27
28 #include "prm.h"
29 #include "common.h"
30 #include "control.h"
31 #include "omap_hwmod.h"
32 #include "omap_device.h"
33 #include "mux.h"
34 #include "mmc.h"
35
36 /*
37 * MSDI_CON_OFFSET: offset in bytes of the MSDI IP block's CON register
38 * from the IP block's base address
39 */
40 #define MSDI_CON_OFFSET 0x0c
41
42 /* Register bitfields in the CON register */
43 #define MSDI_CON_POW_MASK BIT(11)
44 #define MSDI_CON_CLKD_MASK (0x3f << 0)
45 #define MSDI_CON_CLKD_SHIFT 0
46
47 /* MSDI_TARGET_RESET_CLKD: clock divisor to use throughout the reset */
48 #define MSDI_TARGET_RESET_CLKD 0x3ff
49
50 /**
51 * omap_msdi_reset - reset the MSDI IP block
52 * @oh: struct omap_hwmod *
53 *
54 * The MSDI IP block on OMAP2420 has to have both the POW and CLKD
55 * fields set inside its CON register for a reset to complete
56 * successfully. This is not documented in the TRM. For CLKD, we use
57 * the value that results in the lowest possible clock rate, to attempt
58 * to avoid disturbing any cards.
59 */
omap_msdi_reset(struct omap_hwmod * oh)60 int omap_msdi_reset(struct omap_hwmod *oh)
61 {
62 u16 v = 0;
63 int c = 0;
64
65 /* Write to the SOFTRESET bit */
66 omap_hwmod_softreset(oh);
67
68 /* Enable the MSDI core and internal clock */
69 v |= MSDI_CON_POW_MASK;
70 v |= MSDI_TARGET_RESET_CLKD << MSDI_CON_CLKD_SHIFT;
71 omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
72
73 /* Poll on RESETDONE bit */
74 omap_test_timeout((omap_hwmod_read(oh, oh->class->sysc->syss_offs)
75 & SYSS_RESETDONE_MASK),
76 MAX_MODULE_SOFTRESET_WAIT, c);
77
78 if (c == MAX_MODULE_SOFTRESET_WAIT)
79 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
80 __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
81 else
82 pr_debug("%s: %s: softreset in %d usec\n", __func__,
83 oh->name, c);
84
85 /* Disable the MSDI internal clock */
86 v &= ~MSDI_CON_CLKD_MASK;
87 omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
88
89 return 0;
90 }
91