| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* |
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| 3 | * Reset a Jazz machine. |
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| 4 | * |
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| 5 | * We don't trust the firmware so we do it the classic way by poking and |
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| 6 | * stabbing at the keyboard controller ... |
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| 7 | */ |
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| 8 | #include <linux/jiffies.h> |
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| 9 | #include <asm/jazz.h> |
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| 10 | |
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| 11 | #define KBD_STAT_IBF 0x02 /* Keyboard input buffer full */ |
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| 12 | |
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| 13 | static void jazz_write_output(unsigned char val) |
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| 14 | { |
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| 15 | int status; |
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| 16 | |
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| 17 | do { |
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| 18 | status = jazz_kh->command; |
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| 19 | } while (status & KBD_STAT_IBF); |
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| 20 | jazz_kh->data = val; |
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| 21 | } |
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| 22 | |
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| 23 | static void jazz_write_command(unsigned char val) |
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| 24 | { |
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| 25 | int status; |
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| 26 | |
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| 27 | do { |
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| 28 | status = jazz_kh->command; |
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| 29 | } while (status & KBD_STAT_IBF); |
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| 30 | jazz_kh->command = val; |
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| 31 | } |
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| 32 | |
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| 33 | static unsigned char jazz_read_status(void) |
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| 34 | { |
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| 35 | return jazz_kh->command; |
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| 36 | } |
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| 37 | |
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| 38 | static inline void kb_wait(void) |
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| 39 | { |
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| 40 | unsigned long start = jiffies; |
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| 41 | unsigned long timeout = start + HZ/2; |
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| 42 | |
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| 43 | do { |
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| 44 | if (! (jazz_read_status() & 0x02)) |
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| 45 | return; |
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| 46 | } while (time_before_eq(jiffies, timeout)); |
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| 47 | } |
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| 48 | |
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| 49 | void jazz_machine_restart(char *command) |
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| 50 | { |
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| 51 | while(1) { |
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| 52 | kb_wait(); |
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| 53 | jazz_write_command(val: 0xd1); |
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| 54 | kb_wait(); |
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| 55 | jazz_write_output(val: 0x00); |
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| 56 | } |
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| 57 | } |
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| 58 | |
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