1/*
2 * arch/sh/mm/tlb-urb.c
3 *
4 * TLB entry wiring helpers for URB-equipped parts.
5 *
6 * Copyright (C) 2010  Matt Fleming
7 *
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License.  See the file "COPYING" in the main directory of this archive
10 * for more details.
11 */
12#include <linux/mm.h>
13#include <linux/io.h>
14#include <asm/tlb.h>
15#include <asm/mmu_context.h>
16
17/*
18 * Load the entry for 'addr' into the TLB and wire the entry.
19 */
20void tlb_wire_entry(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
21{
22	unsigned long status, flags;
23	int urb;
24
25	local_irq_save(flags);
26
27	status = __raw_readl(MMUCR);
28	urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
29	status &= ~MMUCR_URC;
30
31	/*
32	 * Make sure we're not trying to wire the last TLB entry slot.
33	 */
34	BUG_ON(!--urb);
35
36	urb = urb % MMUCR_URB_NENTRIES;
37
38	/*
39	 * Insert this entry into the highest non-wired TLB slot (via
40	 * the URC field).
41	 */
42	status |= (urb << MMUCR_URC_SHIFT);
43	__raw_writel(status, MMUCR);
44	ctrl_barrier();
45
46	/* Load the entry into the TLB */
47	__update_tlb(vma, addr, pte);
48
49	/* ... and wire it up. */
50	status = __raw_readl(MMUCR);
51
52	status &= ~MMUCR_URB;
53	status |= (urb << MMUCR_URB_SHIFT);
54
55	__raw_writel(status, MMUCR);
56	ctrl_barrier();
57
58	local_irq_restore(flags);
59}
60
61/*
62 * Unwire the last wired TLB entry.
63 *
64 * It should also be noted that it is not possible to wire and unwire
65 * TLB entries in an arbitrary order. If you wire TLB entry N, followed
66 * by entry N+1, you must unwire entry N+1 first, then entry N. In this
67 * respect, it works like a stack or LIFO queue.
68 */
69void tlb_unwire_entry(void)
70{
71	unsigned long status, flags;
72	int urb;
73
74	local_irq_save(flags);
75
76	status = __raw_readl(MMUCR);
77	urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
78	status &= ~MMUCR_URB;
79
80	/*
81	 * Make sure we're not trying to unwire a TLB entry when none
82	 * have been wired.
83	 */
84	BUG_ON(urb++ == MMUCR_URB_NENTRIES);
85
86	urb = urb % MMUCR_URB_NENTRIES;
87
88	status |= (urb << MMUCR_URB_SHIFT);
89	__raw_writel(status, MMUCR);
90	ctrl_barrier();
91
92	local_irq_restore(flags);
93}
94