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cpu/sam0_common/periph/spi: power off spi bus on release

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This commit is contained in:
Daniel Lockau 2019-11-22 14:22:36 +01:00
parent 8424d1845b
commit c5ad13cb18
1 changed files with 17 additions and 12 deletions
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29
cpu/sam0_common/periph/spi.c
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@ -126,20 +126,18 @@ int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
/* power on the device */
poweron(bus);
/* configuration did not change */
if (dev(bus)->BAUD.reg == baud && dev(bus)->CTRLA.reg == ctrla) {
return SPI_OK;
/* first configuration or reconfiguration after altered device usage */
if (dev(bus)->BAUD.reg != baud || dev(bus)->CTRLA.reg != ctrla) {
/* disable the device */
dev(bus)->CTRLA.reg &= ~(SERCOM_SPI_CTRLA_ENABLE);
while (dev(bus)->SYNCBUSY.reg & SERCOM_SPI_SYNCBUSY_ENABLE) {}
dev(bus)->BAUD.reg = baud;
dev(bus)->CTRLA.reg = ctrla;
/* no synchronization needed here, the enable synchronization below
* acts as a write-synchronization for both registers */
}
/* disable the device */
dev(bus)->CTRLA.reg &= ~(SERCOM_SPI_CTRLA_ENABLE);
while (dev(bus)->SYNCBUSY.reg & SERCOM_SPI_SYNCBUSY_ENABLE) {}
dev(bus)->BAUD.reg = baud;
dev(bus)->CTRLA.reg = ctrla;
/* also no synchronization needed here, as CTRLA is write-synchronized */
/* finally enable the device */
dev(bus)->CTRLA.reg |= SERCOM_SPI_CTRLA_ENABLE;
while (dev(bus)->SYNCBUSY.reg & SERCOM_SPI_SYNCBUSY_ENABLE) {}
@ -149,6 +147,13 @@ int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
void spi_release(spi_t bus)
{
/* disable the device */
dev(bus)->CTRLA.reg &= ~(SERCOM_SPI_CTRLA_ENABLE);
while (dev(bus)->SYNCBUSY.reg & SERCOM_SPI_SYNCBUSY_ENABLE) {}
/* power off the device */
poweroff(bus);
/* release access to the device */
mutex_unlock(&locks[bus]);
}