1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * MSDI IP block reset
4 *
5 * Copyright (C) 2012 Texas Instruments, Inc.
6 * Paul Walmsley
7 *
8 * XXX What about pad muxing?
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/err.h>
13
14 #include "prm.h"
15 #include "common.h"
16 #include "control.h"
17 #include "omap_hwmod.h"
18 #include "omap_device.h"
19 #include "mmc.h"
20
21 /*
22 * MSDI_CON_OFFSET: offset in bytes of the MSDI IP block's CON register
23 * from the IP block's base address
24 */
25 #define MSDI_CON_OFFSET 0x0c
26
27 /* Register bitfields in the CON register */
28 #define MSDI_CON_POW_MASK BIT(11)
29 #define MSDI_CON_CLKD_MASK (0x3f << 0)
30 #define MSDI_CON_CLKD_SHIFT 0
31
32 /* MSDI_TARGET_RESET_CLKD: clock divisor to use throughout the reset */
33 #define MSDI_TARGET_RESET_CLKD 0x3ff
34
35 /**
36 * omap_msdi_reset - reset the MSDI IP block
37 * @oh: struct omap_hwmod *
38 *
39 * The MSDI IP block on OMAP2420 has to have both the POW and CLKD
40 * fields set inside its CON register for a reset to complete
41 * successfully. This is not documented in the TRM. For CLKD, we use
42 * the value that results in the lowest possible clock rate, to attempt
43 * to avoid disturbing any cards.
44 */
45 int omap_msdi_reset(struct omap_hwmod *oh)
46 {
47 u16 v = 0;
48 int c = 0;
49
50 /* Write to the SOFTRESET bit */
51 omap_hwmod_softreset(oh);
52
53 /* Enable the MSDI core and internal clock */
54 v |= MSDI_CON_POW_MASK;
55 v |= MSDI_TARGET_RESET_CLKD << MSDI_CON_CLKD_SHIFT;
56 omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
57
58 /* Poll on RESETDONE bit */
59 omap_test_timeout((omap_hwmod_read(oh, oh->class->sysc->syss_offs)
60 & SYSS_RESETDONE_MASK),
61 MAX_MODULE_SOFTRESET_WAIT, c);
62
63 if (c == MAX_MODULE_SOFTRESET_WAIT)
64 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
65 __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
66 else
67 pr_debug("%s: %s: softreset in %d usec\n", __func__,
68 oh->name, c);
69
70 /* Disable the MSDI internal clock */
71 v &= ~MSDI_CON_CLKD_MASK;
72 omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
73
74 return 0;
75 }