1 #ifndef MCA_DMA_H
2 #define MCA_DMA_H
3
4 #include <asm/io.h>
5 #include <linux/ioport.h>
6
7 /*
8 * Microchannel specific DMA stuff. DMA on an MCA machine is fairly similar to
9 * standard PC dma, but it certainly has its quirks. DMA register addresses
10 * are in a different place and there are some added functions. Most of this
11 * should be pretty obvious on inspection. Note that the user must divide
12 * count by 2 when using 16-bit dma; that is not handled by these functions.
13 *
14 * Ramen Noodles are yummy.
15 *
16 * 1998 Tymm Twillman <tymm@computer.org>
17 */
18
19 /*
20 * Registers that are used by the DMA controller; FN is the function register
21 * (tell the controller what to do) and EXE is the execution register (how
22 * to do it)
23 */
24
25 #define MCA_DMA_REG_FN 0x18
26 #define MCA_DMA_REG_EXE 0x1A
27
28 /*
29 * Functions that the DMA controller can do
30 */
31
32 #define MCA_DMA_FN_SET_IO 0x00
33 #define MCA_DMA_FN_SET_ADDR 0x20
34 #define MCA_DMA_FN_GET_ADDR 0x30
35 #define MCA_DMA_FN_SET_COUNT 0x40
36 #define MCA_DMA_FN_GET_COUNT 0x50
37 #define MCA_DMA_FN_GET_STATUS 0x60
38 #define MCA_DMA_FN_SET_MODE 0x70
39 #define MCA_DMA_FN_SET_ARBUS 0x80
40 #define MCA_DMA_FN_MASK 0x90
41 #define MCA_DMA_FN_RESET_MASK 0xA0
42 #define MCA_DMA_FN_MASTER_CLEAR 0xD0
43
44 /*
45 * Modes (used by setting MCA_DMA_FN_MODE in the function register)
46 *
47 * Note that the MODE_READ is read from memory (write to device), and
48 * MODE_WRITE is vice-versa.
49 */
50
51 #define MCA_DMA_MODE_XFER 0x04 /* read by default */
52 #define MCA_DMA_MODE_READ 0x04 /* same as XFER */
53 #define MCA_DMA_MODE_WRITE 0x08 /* OR with MODE_XFER to use */
54 #define MCA_DMA_MODE_IO 0x01 /* DMA from IO register */
55 #define MCA_DMA_MODE_16 0x40 /* 16 bit xfers */
56
57
58 /**
59 * mca_enable_dma - channel to enable DMA on
60 * @dmanr: DMA channel
61 *
62 * Enable the MCA bus DMA on a channel. This can be called from
63 * IRQ context.
64 */
65
66 static __inline__ void mca_enable_dma(unsigned int dmanr)
67 {
68 outb(MCA_DMA_FN_RESET_MASK | dmanr, MCA_DMA_REG_FN);
69 }
70
71 /**
72 * mca_disble_dma - channel to disable DMA on
73 * @dmanr: DMA channel
74 *
75 * Enable the MCA bus DMA on a channel. This can be called from
76 * IRQ context.
77 */
78
79 static __inline__ void mca_disable_dma(unsigned int dmanr)
80 {
81 outb(MCA_DMA_FN_MASK | dmanr, MCA_DMA_REG_FN);
82 }
83
84 /**
85 * mca_set_dma_addr - load a 24bit DMA address
86 * @dmanr: DMA channel
87 * @a: 24bit bus address
88 *
89 * Load the address register in the DMA controller. This has a 24bit
90 * limitation (16Mb).
91 */
92
93 static __inline__ void mca_set_dma_addr(unsigned int dmanr, unsigned int a)
94 {
95 outb(MCA_DMA_FN_SET_ADDR | dmanr, MCA_DMA_REG_FN);
96 outb(a & 0xff, MCA_DMA_REG_EXE);
97 outb((a >> 8) & 0xff, MCA_DMA_REG_EXE);
98 outb((a >> 16) & 0xff, MCA_DMA_REG_EXE);
99 }
100
101 /**
102 * mca_get_dma_addr - load a 24bit DMA address
103 * @dmanr: DMA channel
104 *
105 * Read the address register in the DMA controller. This has a 24bit
106 * limitation (16Mb). The return is a bus address.
107 */
108
109 static __inline__ unsigned int mca_get_dma_addr(unsigned int dmanr)
110 {
111 unsigned int addr;
112
113 outb(MCA_DMA_FN_GET_ADDR | dmanr, MCA_DMA_REG_FN);
114 addr = inb(MCA_DMA_REG_EXE);
115 addr |= inb(MCA_DMA_REG_EXE) << 8;
116 addr |= inb(MCA_DMA_REG_EXE) << 16;
117
118 return addr;
119 }
120
121 /**
122 * mca_set_dma_count - load a 16bit transfer count
123 * @dmanr: DMA channel
124 * @count: count
125 *
126 * Set the DMA count for this channel. This can be up to 64Kbytes.
127 * Setting a count of zero will not do what you expect.
128 */
129
130 static __inline__ void mca_set_dma_count(unsigned int dmanr, unsigned int count)
131 {
132 count--; /* transfers one more than count -- correct for this */
133
134 outb(MCA_DMA_FN_SET_COUNT | dmanr, MCA_DMA_REG_FN);
135 outb(count & 0xff, MCA_DMA_REG_EXE);
136 outb((count >> 8) & 0xff, MCA_DMA_REG_EXE);
137 }
138
139 /**
140 * mca_get_dma_residue - get the remaining bytes to transfer
141 * @dmanr: DMA channel
142 *
143 * This function returns the number of bytes left to transfer
144 * on this DMA channel.
145 */
146
147 static __inline__ unsigned int mca_get_dma_residue(unsigned int dmanr)
148 {
149 unsigned short count;
150
151 outb(MCA_DMA_FN_GET_COUNT | dmanr, MCA_DMA_REG_FN);
152 count = 1 + inb(MCA_DMA_REG_EXE);
153 count += inb(MCA_DMA_REG_EXE) << 8;
154
155 return count;
156 }
157
158 /**
159 * mca_set_dma_io - set the port for an I/O transfer
160 * @dmanr: DMA channel
161 * @io_addr: an I/O port number
162 *
163 * Unlike the ISA bus DMA controllers the DMA on MCA bus can transfer
164 * with an I/O port target.
165 */
166
167 static __inline__ void mca_set_dma_io(unsigned int dmanr, unsigned int io_addr)
168 {
169 /*
170 * DMA from a port address -- set the io address
171 */
172
173 outb(MCA_DMA_FN_SET_IO | dmanr, MCA_DMA_REG_FN);
174 outb(io_addr & 0xff, MCA_DMA_REG_EXE);
175 outb((io_addr >> 8) & 0xff, MCA_DMA_REG_EXE);
176 }
177
178 /**
179 * mca_set_dma_mode - set the DMA mode
180 * @dmanr: DMA channel
181 * @mode: mode to set
182 *
183 * The DMA controller supports several modes. The mode values you can
184 * set are :
185 *
186 * %MCA_DMA_MODE_READ when reading from the DMA device.
187 *
188 * %MCA_DMA_MODE_WRITE to writing to the DMA device.
189 *
190 * %MCA_DMA_MODE_IO to do DMA to or from an I/O port.
191 *
192 * %MCA_DMA_MODE_16 to do 16bit transfers.
193 *
194 */
195
196 static __inline__ void mca_set_dma_mode(unsigned int dmanr, unsigned int mode)
197 {
198 outb(MCA_DMA_FN_SET_MODE | dmanr, MCA_DMA_REG_FN);
199 outb(mode, MCA_DMA_REG_EXE);
200 }
201
202 #endif MCA_DMA_H
203
This page was automatically generated by the
LXR engine.
Visit the LXR main site for more
information.