diff options
Diffstat (limited to 'src/pc80/mc146818rtc.c')
| -rw-r--r-- | src/pc80/mc146818rtc.c | 160 |
1 files changed, 124 insertions, 36 deletions
diff --git a/src/pc80/mc146818rtc.c b/src/pc80/mc146818rtc.c index 0baa389c1f..55f161f29e 100644 --- a/src/pc80/mc146818rtc.c +++ b/src/pc80/mc146818rtc.c @@ -197,41 +197,69 @@ void rtc_init(int invalid) #if USE_OPTION_TABLE == 1 -/* This routine returns the value of the requested bits - input bit = bit count from the beginning of the cmos image - length = number of bits to include in the value - ret = a character pointer to where the value is to be returned - output the value placed in ret - returns 0 = successful, -1 = an error occurred -*/ -static int get_cmos_value(unsigned long bit, unsigned long length, void *vret) +/* + * Functions to save/return values stored in the 256byte cmos. + * + * To be able to use space maximally we want to only store as many bits as + * needed, and not be limited by byte boundaries. We therefor clamp the size + * down to an unsigned int. Since the values that we are allowed to touch are + * either an enum or a hexadecimal value, this size should suit most purposes. + * + * These two functions are doing bitshifting, and are therefor a bit + * nontrivial. To understand these operations, first read the ones outside the + * loop. The ones inside the loop are just adding i to the same calculations, + * with the shift twice inverted, as negative shifts aren't nice. + */ +static unsigned int +get_cmos_value(int bit, int length) { - unsigned char *ret; - unsigned long byte,byte_bit; - unsigned long i; - unsigned char uchar; - - /* The table is checked when it is built to ensure all - values are valid. */ - ret = vret; - byte=bit/8; /* find the byte where the data starts */ - byte_bit=bit%8; /* find the bit in the byte where the data starts */ - if(length<9) { /* one byte or less */ - uchar = cmos_read(byte); /* load the byte */ - uchar >>= byte_bit; /* shift the bits to byte align */ - /* clear unspecified bits */ - ret[0] = uchar & ((1 << length) -1); - } - else { /* more that one byte so transfer the whole bytes */ - for(i=0;length;i++,length-=8,byte++) { - /* load the byte */ - ret[i]=cmos_read(byte); - } + unsigned int tmp; + int i; + + /* negative left shift --> right shift */ + tmp = cmos_read(bit / 8) >> (bit % 8); + + for (i = 1; (8 * i) < ((bit % 8) + length); i++) + tmp |= cmos_read((bit / 8) + i) << ((8 * i) - (bit % 8)); + + /* 1 << 32 - 1 isn't cool inside an int */ + if (length != 32) + tmp &= (1 << length) - 1; + + return tmp; +} + +static void +set_cmos_value(int bit, int length, unsigned int value) +{ + unsigned int mask; + unsigned char cmos; + int i; + + /* 1 << 32 - 1 isn't cool inside an int */ + if (length != 32) + mask = (1 << length) - 1; + else + mask = -1; + + value &= mask; + + /* negative right shifts --> left shifts */ + cmos = cmos_read(bit / 8); + cmos &= ~(mask << (bit % 8)); + cmos |= value << (bit % 8); + cmos_write(cmos, bit / 8); + + for (i = 1; (8 * i) < ((bit % 8) + length); i++) { + cmos = cmos_read((bit / 8) + i); + cmos &= ~(mask >> ((8 * i) - (bit % 8))); + cmos |= value >> ((8 * i) - (bit % 8)); + cmos_write(cmos, (bit / 8) + i); } - return 0; } -int get_option(void *dest, char *name) +int +get_option(char *name, unsigned int *value) { extern struct cmos_option_table option_table; struct cmos_option_table *ct; @@ -241,7 +269,7 @@ int get_option(void *dest, char *name) /* Figure out how long name is */ namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); - + /* find the requested entry record */ ct=&option_table; ce=(struct cmos_entries*)((unsigned char *)ct + ct->header_length); @@ -256,12 +284,72 @@ int get_option(void *dest, char *name) printk_err("ERROR: No cmos option '%s'\n", name); return(-2); } - - if(get_cmos_value(ce->bit, ce->length, dest)) - return(-3); + + if (ce->length > 32) { + printk_err("ERROR: cmos option '%s' is too large.\n", name); + return -3; + } + + + *value = get_cmos_value(ce->bit, ce->length); + if(!rtc_checksum_valid(LB_CKS_RANGE_START, - LB_CKS_RANGE_END,LB_CKS_LOC)) + LB_CKS_RANGE_END,LB_CKS_LOC)) return(-4); return(0); } + +int +set_option(char *name, unsigned int value) +{ + extern struct cmos_option_table option_table; + struct cmos_option_table *ct; + struct cmos_entries *ce; + size_t namelen; + int found = 0; + + /* Figure out how long name is */ + namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); + + /* find the requested entry record */ + ct = &option_table; + ce = (struct cmos_entries*) ((unsigned char *) ct + ct->header_length); + + for(;ce->tag==LB_TAG_OPTION; + ce=(struct cmos_entries*)((unsigned char *)ce + ce->size)) { + if (memcmp(ce->name, name, namelen) == 0) { + found=1; + break; + } + } + + if (!found) { + printk_err("ERROR: Unknown cmos option '%s'\n", name); + return(-2); + } + + if (ce->length > 32) { + printk_err("ERROR: cmos option '%s' is too large.\n", name); + return -3; + } + + set_cmos_value(ce->bit, ce->length, value); + + /* We should not update the checksum here. */ + + return 0; +} +#else +int +get_option(char *name, unsigned int *value) +{ + return -2; +} + +int +set_option(char *name, unsigned int value) +{ + return -2; +} + #endif /* USE_OPTION_TABLE */ |