tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/*
2 * Minimal serial functions needed to send messages out a MPC52xx
3 * Programmable Serial Controller (PSC).
4 *
5 * Author: Dale Farnsworth <dfarnsworth@mvista.com>
6 *
7 * 2003-2004 (c) MontaVista, Software, Inc. This file is licensed under the
8 * terms of the GNU General Public License version 2. This program is licensed
9 * "as is" without any warranty of any kind, whether express or implied.
10 */
11
12#include <linux/types.h>
13#include <asm/uaccess.h>
14#include <asm/mpc52xx.h>
15#include <asm/mpc52xx_psc.h>
16#include <asm/serial.h>
17#include <asm/io.h>
18#include <asm/time.h>
19
20
21#ifdef MPC52xx_PF_CONSOLE_PORT
22#define MPC52xx_CONSOLE MPC52xx_PSCx_OFFSET(MPC52xx_PF_CONSOLE_PORT)
23#define MPC52xx_PSC_CONFIG_SHIFT ((MPC52xx_PF_CONSOLE_PORT-1)<<2)
24#else
25#error "MPC52xx_PF_CONSOLE_PORT not defined"
26#endif
27
28static struct mpc52xx_psc __iomem *psc =
29 (struct mpc52xx_psc __iomem *) MPC52xx_PA(MPC52xx_CONSOLE);
30
31/* The decrementer counts at the system bus clock frequency
32 * divided by four. The most accurate time base is connected to the
33 * rtc. We read the decrementer change during one rtc tick
34 * and multiply by 4 to get the system bus clock frequency. Since a
35 * rtc tick is one seconds, and that's pretty long, we change the rtc
36 * dividers temporarily to set them 64x faster ;)
37 */
38static int
39mpc52xx_ipbfreq(void)
40{
41 struct mpc52xx_rtc __iomem *rtc =
42 (struct mpc52xx_rtc __iomem *) MPC52xx_PA(MPC52xx_RTC_OFFSET);
43 struct mpc52xx_cdm __iomem *cdm =
44 (struct mpc52xx_cdm __iomem *) MPC52xx_PA(MPC52xx_CDM_OFFSET);
45 int current_time, previous_time;
46 int tbl_start, tbl_end;
47 int xlbfreq, ipbfreq;
48
49 out_be32(&rtc->dividers, 0x8f1f0000); /* Set RTC 64x faster */
50 previous_time = in_be32(&rtc->time);
51 while ((current_time = in_be32(&rtc->time)) == previous_time) ;
52 tbl_start = get_tbl();
53 previous_time = current_time;
54 while ((current_time = in_be32(&rtc->time)) == previous_time) ;
55 tbl_end = get_tbl();
56 out_be32(&rtc->dividers, 0xffff0000); /* Restore RTC */
57
58 xlbfreq = (tbl_end - tbl_start) << 8;
59 ipbfreq = (in_8(&cdm->ipb_clk_sel) & 1) ? xlbfreq / 2 : xlbfreq;
60
61 return ipbfreq;
62}
63
64unsigned long
65serial_init(int ignored, void *ignored2)
66{
67 struct mpc52xx_gpio __iomem *gpio =
68 (struct mpc52xx_gpio __iomem *) MPC52xx_PA(MPC52xx_GPIO_OFFSET);
69 int divisor;
70 int mode1;
71 int mode2;
72 u32 val32;
73
74 static int been_here = 0;
75
76 if (been_here)
77 return 0;
78
79 been_here = 1;
80
81 val32 = in_be32(&gpio->port_config);
82 val32 &= ~(0x7 << MPC52xx_PSC_CONFIG_SHIFT);
83 val32 |= MPC52xx_GPIO_PSC_CONFIG_UART_WITHOUT_CD
84 << MPC52xx_PSC_CONFIG_SHIFT;
85 out_be32(&gpio->port_config, val32);
86
87 out_8(&psc->command, MPC52xx_PSC_RST_TX
88 | MPC52xx_PSC_RX_DISABLE | MPC52xx_PSC_TX_ENABLE);
89 out_8(&psc->command, MPC52xx_PSC_RST_RX);
90
91 out_be32(&psc->sicr, 0x0);
92 out_be16(&psc->mpc52xx_psc_clock_select, 0xdd00);
93 out_be16(&psc->tfalarm, 0xf8);
94
95 out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1
96 | MPC52xx_PSC_RX_ENABLE
97 | MPC52xx_PSC_TX_ENABLE);
98
99 divisor = ((mpc52xx_ipbfreq()
100 / (CONFIG_SERIAL_MPC52xx_CONSOLE_BAUD * 16)) + 1) >> 1;
101
102 mode1 = MPC52xx_PSC_MODE_8_BITS | MPC52xx_PSC_MODE_PARNONE
103 | MPC52xx_PSC_MODE_ERR;
104 mode2 = MPC52xx_PSC_MODE_ONE_STOP;
105
106 out_8(&psc->ctur, divisor>>8);
107 out_8(&psc->ctlr, divisor);
108 out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
109 out_8(&psc->mode, mode1);
110 out_8(&psc->mode, mode2);
111
112 return 0; /* ignored */
113}
114
115void
116serial_putc(void *ignored, const char c)
117{
118 serial_init(0, NULL);
119
120 while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_TXEMP)) ;
121 out_8(&psc->mpc52xx_psc_buffer_8, c);
122 while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_TXEMP)) ;
123}
124
125char
126serial_getc(void *ignored)
127{
128 while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_RXRDY)) ;
129
130 return in_8(&psc->mpc52xx_psc_buffer_8);
131}
132
133int
134serial_tstc(void *ignored)
135{
136 return (in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_RXRDY) != 0;
137}