go-packages/go-rpio
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This commit is contained in:
Drahoslav 2017-11-14 22:33:04 +01:00
parent b604d03178
commit cdcd97f287
1 changed files with 29 additions and 29 deletions
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58
rpio.go
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@ -74,19 +74,19 @@ type Pull uint8
// Memory offsets for gpio, see the spec for more details // Memory offsets for gpio, see the spec for more details
const ( const (
bcm2835Base = 0x20000000 bcm2835Base = 0x20000000
gpioOffset = 0x200000 gpioOffset = 0x200000
clkOffset = 0x101000 clkOffset = 0x101000
memLength = 4096 memLength = 4096
) )
var ( var (
base int64 base int64
gpioBase int64 gpioBase int64
clkBase int64 clkBase int64
) )
func init () { func init() {
base = getBase() base = getBase()
gpioBase = base + gpioOffset gpioBase = base + gpioOffset
clkBase = base + clkOffset clkBase = base + clkOffset
@ -114,11 +114,11 @@ const (
// Arrays for 8 / 32 bit access to memory and a semaphore for write locking // Arrays for 8 / 32 bit access to memory and a semaphore for write locking
var ( var (
memlock sync.Mutex memlock sync.Mutex
gpioMem []uint32 gpioMem []uint32
clkMem []uint32 clkMem []uint32
gpioMem8 []uint8 gpioMem8 []uint8
clkMem8 []uint8 clkMem8 []uint8
) )
// Set pin as Input // Set pin as Input
@ -247,7 +247,7 @@ func ReadPin(pin Pin) State {
// Input level register offset (13 / 14 depending on bank) // Input level register offset (13 / 14 depending on bank)
levelReg := uint8(pin)/32 + 13 levelReg := uint8(pin)/32 + 13
if (gpioMem[levelReg] & (1 << uint8(pin & 31))) != 0 { if (gpioMem[levelReg] & (1 << uint8(pin&31))) != 0 {
return High return High
} }
@ -294,7 +294,6 @@ func PullMode(pin Pin, pull Pull) {
} }
// Set clock speed for given pin // Set clock speed for given pin
// //
// freq should be in range 4688Hz - 19.2MHz to prevent unexpected behavior // freq should be in range 4688Hz - 19.2MHz to prevent unexpected behavior
@ -316,17 +315,17 @@ func SetClock(pin Pin, freq int) {
clkCtlReg := 0x70 clkCtlReg := 0x70
clkDivReg := 0x74 clkDivReg := 0x74
switch pin { switch pin {
case 4, 20, 32, 34: // clk0 case 4, 20, 32, 34: // clk0
clkCtlReg += 0 clkCtlReg += 0
clkDivReg += 0 clkDivReg += 0
case 5, 21, 42, 44: // clk1 case 5, 21, 42, 44: // clk1
clkCtlReg += 8 clkCtlReg += 8
clkDivReg += 8 clkDivReg += 8
case 6, 43: // clk2 case 6, 43: // clk2
clkCtlReg += 16 clkCtlReg += 16
clkDivReg += 16 clkDivReg += 16
default: default:
return return
} }
memlock.Lock() memlock.Lock()
@ -338,10 +337,11 @@ func SetClock(pin Pin, freq int) {
const src = 0x01 // oscilator const src = 0x01 // oscilator
clkMem[clkCtlReg] = PASSWORD | src // stop gpio clock clkMem[clkCtlReg] = PASSWORD | src // stop gpio clock
for clkMem[clkCtlReg] & busy != 0 {} // ... and wait for clkMem[clkCtlReg]&busy != 0 {
} // ... and wait
clkMem[clkDivReg] = PASSWORD | (divi << 12) | divf // set dividers clkMem[clkDivReg] = PASSWORD | (divi << 12) | divf // set dividers
clkMem[clkCtlReg] = PASSWORD | enab | src // start clock clkMem[clkCtlReg] = PASSWORD | enab | src // start clock
} }
@ -379,10 +379,10 @@ func Open() (err error) {
return nil return nil
} }
func memMap (fd uintptr, offset int64) (mem []uint32, mem8 []byte, err error) { func memMap(fd uintptr, offset int64) (mem []uint32, mem8 []byte, err error) {
mem8, err = syscall.Mmap( mem8, err = syscall.Mmap(
int(fd), int(fd),
base + clkOffset, base+clkOffset,
memLength, memLength,
syscall.PROT_READ|syscall.PROT_WRITE, syscall.PROT_READ|syscall.PROT_WRITE,
syscall.MAP_SHARED, syscall.MAP_SHARED,
@ -402,10 +402,10 @@ func memMap (fd uintptr, offset int64) (mem []uint32, mem8 []byte, err error) {
func Close() error { func Close() error {
memlock.Lock() memlock.Lock()
defer memlock.Unlock() defer memlock.Unlock()
if err := syscall.Munmap(gpioMem8) { if err := syscall.Munmap(gpioMem8); err != nil {
return err return err
} }
if err := syscall.Munmap(clkMem8) { if err := syscall.Munmap(clkMem8); err != nil {
return err return err
} }
return nil return nil