[MIPS] Yosemite: fix uninitialized variable in titan_i2c_xfer()
[linux-2.6.git] / arch / mips / pmc-sierra / yosemite / i2c-yosemite.c
1 /*
2  *  Copyright (C) 2003 PMC-Sierra Inc.
3  *  Author: Manish Lachwani (lachwani@pmc-sierra.com)
4  *
5  *  This program is free software; you can redistribute  it and/or modify it
6  *  under  the terms of  the GNU General  Public License as published by the
7  *  Free Software Foundation;  either version 2 of the  License, or (at your
8  *  option) any later version.
9  *
10  *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
11  *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
12  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
13  *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
14  *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
15  *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
16  *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
17  *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
18  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
19  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
20  *
21  *  You should have received a copy of the  GNU General Public License along
22  *  with this program; if not, write  to the Free Software Foundation, Inc.,
23  *  675 Mass Ave, Cambridge, MA 02139, USA.
24  */
25
26 /*
27  * Detailed Description:
28  *
29  * This block implements the I2C interface to the slave devices like the
30  * Atmel 24C32 EEPROM and the MAX 1619 Sensors device. The I2C Master interface
31  * can be controlled by the SCMB block. And the SCMB block kicks in only when
32  * using the Ethernet Mode of operation and __not__ the SysAD mode
33  *
34  * The SCMB controls the two modes: MDIO and the I2C. The MDIO mode is used to
35  * communicate with the Quad-PHY from Marvel. The I2C is used to communicate
36  * with the I2C slave devices.  It seems that the driver does not explicitly
37  * deal with the control of SDA and SCL serial lines. So, the driver will set
38  * the slave address, drive the command and then the data.  The SCMB will then
39  * control the two serial lines as required.
40  *
41  * It seems the documents are very unclear abt this. Hence, I took some time
42  * out to write the desciption to have an idea of how the I2C can actually
43  * work. Currently, this Linux driver wont be integrated into the generic Linux
44  * I2C framework. And finally, the I2C interface is also known as the 2BI
45  * interface. 2BI means 2-bit interface referring to SDA and SCL serial lines
46  * respectively.
47  *
48  * - Manish Lachwani (12/09/2003)
49  */
50
51 #include "i2c-yosemite.h"
52
53 /*
54  * Poll the I2C interface for the BUSY bit.
55  */
56 static int titan_i2c_poll(void)
57 {
58         int i = 0;
59         unsigned long val = 0;
60
61         for (i = 0; i < TITAN_I2C_MAX_POLL; i++) {
62                 val = TITAN_I2C_READ(TITAN_I2C_COMMAND);
63
64                 if (!(val & 0x8000))
65                         return 0;
66         }
67
68         return TITAN_I2C_ERR_TIMEOUT;
69 }
70
71 /*
72  * Execute the I2C command
73  */
74 int titan_i2c_xfer(unsigned int slave_addr, titan_i2c_command * cmd,
75                    int size, unsigned int *addr)
76 {
77         int loop, bytes = 0, i;
78         unsigned int *write_data, data, *read_data;
79         unsigned long reg_val, val;
80
81         write_data = cmd->data;
82         read_data = addr;
83
84         TITAN_I2C_WRITE(TITAN_I2C_SLAVE_ADDRESS, slave_addr);
85
86         if (cmd->type == TITAN_I2C_CMD_WRITE)
87                 loop = cmd->write_size;
88         else
89                 loop = size;
90
91         while (loop > 0) {
92                 if ((cmd->type == TITAN_I2C_CMD_WRITE) ||
93                     (cmd->type == TITAN_I2C_CMD_READ_WRITE)) {
94
95                         reg_val = TITAN_I2C_DATA;
96                         for (i = 0; i < TITAN_I2C_MAX_WORDS_PER_RW;
97                              ++i, write_data += 2, reg_val += 4) {
98                                 if (bytes < cmd->write_size) {
99                                         data = write_data[0];
100                                         ++data;
101                                 }
102
103                                 if (bytes < cmd->write_size) {
104                                         data = write_data[1];
105                                         ++data;
106                                 }
107
108                                 TITAN_I2C_WRITE(reg_val, data);
109                         }
110                 }
111
112                 TITAN_I2C_WRITE(TITAN_I2C_COMMAND,
113                                 (unsigned int) (cmd->type << 13));
114                 if (titan_i2c_poll() != TITAN_I2C_ERR_OK)
115                         return TITAN_I2C_ERR_TIMEOUT;
116
117                 if ((cmd->type == TITAN_I2C_CMD_READ) ||
118                     (cmd->type == TITAN_I2C_CMD_READ_WRITE)) {
119
120                         reg_val = TITAN_I2C_DATA;
121                         for (i = 0; i < TITAN_I2C_MAX_WORDS_PER_RW;
122                              ++i, read_data += 2, reg_val += 4) {
123                                 data = TITAN_I2C_READ(reg_val);
124
125                                 if (bytes < size) {
126                                         read_data[0] = data & 0xff;
127                                         ++bytes;
128                                 }
129
130                                 if (bytes < size) {
131                                         read_data[1] =
132                                             ((data >> 8) & 0xff);
133                                         ++bytes;
134                                 }
135                         }
136                 }
137
138                 loop -= (TITAN_I2C_MAX_WORDS_PER_RW * 2);
139         }
140
141         /*
142          * Read the Interrupt status and then return the appropriate error code
143          */
144
145         val = TITAN_I2C_READ(TITAN_I2C_INTERRUPTS);
146         if (val & 0x0020)
147                 return TITAN_I2C_ERR_ARB_LOST;
148
149         if (val & 0x0040)
150                 return TITAN_I2C_ERR_NO_RESP;
151
152         if (val & 0x0080)
153                 return TITAN_I2C_ERR_DATA_COLLISION;
154
155         return TITAN_I2C_ERR_OK;
156 }
157
158 /*
159  * Init the I2C subsystem of the PMC-Sierra Yosemite board
160  */
161 int titan_i2c_init(titan_i2c_config * config)
162 {
163         unsigned int val;
164
165         /*
166          * Reset the SCMB and program into the I2C mode
167          */
168         TITAN_I2C_WRITE(TITAN_I2C_SCMB_CONTROL, 0xA000);
169         TITAN_I2C_WRITE(TITAN_I2C_SCMB_CONTROL, 0x2000);
170
171         /*
172          * Configure the filtera and clka values
173          */
174         val = TITAN_I2C_READ(TITAN_I2C_SCMB_CLOCK_A);
175         val |= ((val & ~(0xF000)) | ((config->filtera << 12) & 0xF000));
176         val |= ((val & ~(0x03FF)) | (config->clka & 0x03FF));
177         TITAN_I2C_WRITE(TITAN_I2C_SCMB_CLOCK_A, val);
178
179         /*
180          * Configure the filterb and clkb values
181          */
182         val = TITAN_I2C_READ(TITAN_I2C_SCMB_CLOCK_B);
183         val |= ((val & ~(0xF000)) | ((config->filterb << 12) & 0xF000));
184         val |= ((val & ~(0x03FF)) | (config->clkb & 0x03FF));
185         TITAN_I2C_WRITE(TITAN_I2C_SCMB_CLOCK_B, val);
186
187         return TITAN_I2C_ERR_OK;
188 }