Allow setting the SPI message delay.

This CL adds an interface to set the delay to wait between two SPI
messages.

Bug: 27923916

Change-Id: Idb1fa208b974d489414d63d67ad5fa702e8b03e4

6 files changed, 35 insertions, 1 deletions

diff --git a/daemon/peripheral_manager_client.cc b/daemon/peripheral_manager_client.cc
index e821288..d279a9f 100644
--- a/daemon/peripheral_manager_client.cc
+++ b/daemon/peripheral_manager_client.cc
@@ -235,6 +235,22 @@ Status PeripheralManagerClient::SpiDeviceSetBitsPerWord(const std::string& name,
   return Status::fromServiceSpecificError(EREMOTEIO);
 }
 
+Status PeripheralManagerClient::SpiDeviceSetDelay(const std::string& name,
+                                                  int delay_usecs) {
+  if (!spi_devices_.count(name))
+    return Status::fromServiceSpecificError(EPERM);
+
+  // |delay_usecs| must be positive and fit in an unsigned 16 bit.
+  if (delay_usecs < 0 || delay_usecs > INT16_MAX)
+    return Status::fromServiceSpecificError(EINVAL);
+
+  if (spi_devices_.find(name)->second->SetDelay(
+          static_cast<uint16_t>(delay_usecs)))
+    return Status::ok();
+
+  return Status::fromServiceSpecificError(EREMOTEIO);
+}
+
 Status PeripheralManagerClient::ListLeds(std::vector<std::string>* leds) {
   *leds = LedManager::GetLedManager()->GetLeds();
   return Status::ok();
diff --git a/daemon/peripheral_manager_client.h b/daemon/peripheral_manager_client.h
index 99f3999..23d15c7 100644
--- a/daemon/peripheral_manager_client.h
+++ b/daemon/peripheral_manager_client.h
@@ -92,6 +92,9 @@ class PeripheralManagerClient : public BnPeripheralManagerClient {
   virtual Status SpiDeviceSetBitsPerWord(const std::string& name,
                                          int nbits) override;
 
+  virtual Status SpiDeviceSetDelay(const std::string& name,
+                                   int delay_usecs) override;
+
   virtual Status ListLeds(std::vector<std::string>* leds) override;
 
   virtual Status OpenLed(const std::string& name) override;
diff --git a/daemon/spi_driver.h b/daemon/spi_driver.h
index 3f04e36..700a169 100644
--- a/daemon/spi_driver.h
+++ b/daemon/spi_driver.h
@@ -40,6 +40,7 @@ class SpiDriverInterface {
   virtual bool SetMode(SpiMode mode) = 0;
   virtual bool SetBitJustification(bool lsb_first) = 0;
   virtual bool SetBitsPerWord(uint8_t bits_per_word) = 0;
+  virtual bool SetDelay(uint16_t delay_usecs) = 0;
 };
 
 class SpiDriverInfoBase {
diff --git a/daemon/spi_driver_spidev.cc b/daemon/spi_driver_spidev.cc
index 9a30b21..2ac4844 100644
--- a/daemon/spi_driver_spidev.cc
+++ b/daemon/spi_driver_spidev.cc
@@ -71,6 +71,9 @@ bool SpiDriverSpiDev::Init(uint32_t bus_id, uint32_t cs) {
   }
   speed_hz_ = max_freq;
 
+  // Default to 0 microseconds delay between transfers.
+  delay_usecs_ = 0;
+
   // Default to 8 bits per word.
   bits_per_word_ = 8;
 
@@ -85,7 +88,7 @@ bool SpiDriverSpiDev::Transfer(const void* tx_data, void* rx_data, size_t len) {
   msg.rx_buf = (unsigned long)rx_data;
   msg.speed_hz = speed_hz_;
   msg.bits_per_word = bits_per_word_;
-  msg.delay_usecs = 0;
+  msg.delay_usecs = delay_usecs_;
   msg.len = len;
 
   if (char_interface_->Ioctl(fd_, SPI_IOC_MESSAGE(1), &msg) < 0) {
@@ -161,4 +164,9 @@ bool SpiDriverSpiDev::SetBitsPerWord(uint8_t bits_per_word) {
   return true;
 }
 
+bool SpiDriverSpiDev::SetDelay(uint16_t delay_usecs) {
+  delay_usecs_ = delay_usecs;
+  return true;
+}
+
 }  // namespace android
diff --git a/daemon/spi_driver_spidev.h b/daemon/spi_driver_spidev.h
index 1214e2b..f573fb0 100644
--- a/daemon/spi_driver_spidev.h
+++ b/daemon/spi_driver_spidev.h
@@ -41,6 +41,7 @@ class SpiDriverSpiDev : public SpiDriverInterface {
   bool SetMode(SpiMode mode) override;
   bool SetBitJustification(bool lsb_first) override;
   bool SetBitsPerWord(uint8_t bits_per_word) override;
+  bool SetDelay(uint16_t delay_usecs) override;
 
  private:
   bool GetMaxFrequency(uint32_t* max_freq);
@@ -48,6 +49,7 @@ class SpiDriverSpiDev : public SpiDriverInterface {
   int fd_;
   uint32_t bits_per_word_;
   uint32_t speed_hz_;
+  uint16_t delay_usecs_;
   std::unique_ptr<CharDeviceInterface> char_interface_;
 
   // Used for unit testing and is null in production.
diff --git a/daemon/spi_manager.h b/daemon/spi_manager.h
index 80c9d64..deec13c 100644
--- a/daemon/spi_manager.h
+++ b/daemon/spi_manager.h
@@ -76,6 +76,10 @@ class SpiDevice {
     return bus_->driver_->SetBitsPerWord(bits_per_word);
   }
 
+  bool SetDelay(uint16_t delay_usecs) {
+    return bus_->driver_->SetDelay(delay_usecs);
+  }
+
  private:
   SpiDevBus* bus_;
 };