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  */
tlb_wire_entry(struct vm_area_struct * vma,unsigned long addr,pte_t pte)20 void 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  */
tlb_unwire_entry(void)69 void 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