drivers/misc/mediatek/gpu/mt8127/mali/mali/common/mali_osk_bitops.h

   1 /*
   2  * This confidential and proprietary software may be used only as
   3  * authorised by a licensing agreement from ARM Limited
   4  * (C) COPYRIGHT 2008-2010, 2013 ARM Limited
   5  * ALL RIGHTS RESERVED
   6  * The entire notice above must be reproduced on all authorised
   7  * copies and copies may only be made to the extent permitted
   8  * by a licensing agreement from ARM Limited.
   9  */
  10
  11 /**
  12  * @file mali_osk_bitops.h
  13  * Implementation of the OS abstraction layer for the kernel device driver
  14  */
  15
  16 #ifndef __MALI_OSK_BITOPS_H__
  17 #define __MALI_OSK_BITOPS_H__
  18
  19 #ifdef __cplusplus
  20 extern "C" {
  21 #endif
  22
  23 MALI_STATIC_INLINE void _mali_internal_clear_bit( u32 bit, u32 *addr )
  24 {
  25         MALI_DEBUG_ASSERT( bit < 32 );
  26         MALI_DEBUG_ASSERT( NULL != addr );
  27
  28         (*addr) &= ~(1 << bit);
  29 }
  30
  31 MALI_STATIC_INLINE void _mali_internal_set_bit( u32 bit, u32 *addr )
  32 {
  33         MALI_DEBUG_ASSERT( bit < 32 );
  34         MALI_DEBUG_ASSERT( NULL != addr );
  35
  36         (*addr) |= (1 << bit);
  37 }
  38
  39 MALI_STATIC_INLINE u32 _mali_internal_test_bit( u32 bit, u32 value )
  40 {
  41         MALI_DEBUG_ASSERT( bit < 32 );
  42         return value & (1 << bit);
  43 }
  44
  45 MALI_STATIC_INLINE int _mali_internal_find_first_zero_bit( u32 value )
  46 {
  47         u32 inverted;
  48         u32 negated;
  49         u32 isolated;
  50         u32 leading_zeros;
  51
  52         /* Begin with xxx...x0yyy...y, where ys are 1, number of ys is in range  0..31 */
  53         inverted = ~value; /* zzz...z1000...0 */
  54         /* Using count_trailing_zeros on inverted value -
  55          * See ARM System Developers Guide for details of count_trailing_zeros */
  56
  57         /* Isolate the zero: it is preceeded by a run of 1s, so add 1 to it */
  58         negated = (u32)-inverted ; /* -a == ~a + 1 (mod 2^n) for n-bit numbers */
  59         /* negated = xxx...x1000...0 */
  60
  61         isolated = negated & inverted ; /* xxx...x1000...0 & zzz...z1000...0, zs are ~xs */
  62         /* And so the first zero bit is in the same position as the 1 == number of 1s that preceeded it
  63          * Note that the output is zero if value was all 1s */
  64
  65         leading_zeros = _mali_osk_clz( isolated );
  66
  67         return 31 - leading_zeros;
  68 }
  69
  70
  71 /** @defgroup _mali_osk_bitops OSK Non-atomic Bit-operations
  72  * @{ */
  73
  74 /**
  75  * These bit-operations do not work atomically, and so locks must be used if
  76  * atomicity is required.
  77  *
  78  * Reference implementations for Little Endian are provided, and so it should
  79  * not normally be necessary to re-implement these. Efficient bit-twiddling
  80  * techniques are used where possible, implemented in portable C.
  81  *
  82  * Note that these reference implementations rely on _mali_osk_clz() being
  83  * implemented.
  84  */
  85
  86 /** @brief Clear a bit in a sequence of 32-bit words
  87  * @param nr bit number to clear, starting from the (Little-endian) least
  88  * significant bit
  89  * @param addr starting point for counting.
  90  */
  91 MALI_STATIC_INLINE void _mali_osk_clear_nonatomic_bit( u32 nr, u32 *addr )
  92 {
  93         addr += nr >> 5; /* find the correct word */
  94         nr = nr & ((1 << 5)-1); /* The bit number within the word */
  95
  96         _mali_internal_clear_bit( nr, addr );
  97 }
  98
  99 /** @brief Set a bit in a sequence of 32-bit words
 100  * @param nr bit number to set, starting from the (Little-endian) least
 101  * significant bit
 102  * @param addr starting point for counting.
 103  */
 104 MALI_STATIC_INLINE void _mali_osk_set_nonatomic_bit( u32 nr, u32 *addr )
 105 {
 106         addr += nr >> 5; /* find the correct word */
 107         nr = nr & ((1 << 5)-1); /* The bit number within the word */
 108
 109         _mali_internal_set_bit( nr, addr );
 110 }
 111
 112 /** @brief Test a bit in a sequence of 32-bit words
 113  * @param nr bit number to test, starting from the (Little-endian) least
 114  * significant bit
 115  * @param addr starting point for counting.
 116  * @return zero if bit was clear, non-zero if set. Do not rely on the return
 117  * value being related to the actual word under test.
 118  */
 119 MALI_STATIC_INLINE u32 _mali_osk_test_bit( u32 nr, u32 *addr )
 120 {
 121         addr += nr >> 5; /* find the correct word */
 122         nr = nr & ((1 << 5)-1); /* The bit number within the word */
 123
 124         return _mali_internal_test_bit( nr, *addr );
 125 }
 126
 127 /* Return maxbit if not found */
 128 /** @brief Find the first zero bit in a sequence of 32-bit words
 129  * @param addr starting point for search.
 130  * @param maxbit the maximum number of bits to search
 131  * @return the number of the first zero bit found, or maxbit if none were found
 132  * in the specified range.
 133  */
 134 MALI_STATIC_INLINE u32 _mali_osk_find_first_zero_bit( const u32 *addr, u32 maxbit )
 135 {
 136         u32 total;
 137
 138         for ( total = 0; total < maxbit; total += 32, ++addr ) {
 139                 int result;
 140                 result = _mali_internal_find_first_zero_bit( *addr );
 141
 142                 /* non-negative signifies the bit was found */
 143                 if ( result >= 0 ) {
 144                         total += (u32)result;
 145                         break;
 146                 }
 147         }
 148
 149         /* Now check if we reached maxbit or above */
 150         if ( total >= maxbit ) {
 151                 total = maxbit;
 152         }
 153
 154         return total; /* either the found bit nr, or maxbit if not found */
 155 }
 156 /** @} */ /* end group _mali_osk_bitops */
 157
 158 #ifdef __cplusplus
 159 }
 160 #endif
 161
 162 #endif /* __MALI_OSK_BITOPS_H__ */