75 lines
2.3 KiB
C++
75 lines
2.3 KiB
C++
// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "i2c_sam0.h"
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static constexpr uint8_t kCommand = 0xFE;
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void I2C::init() {
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID_SERCOM3_CORE | GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0;
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PM->APBCMASK.bit.SERCOM3_ = 1;
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regs_->CTRLA.bit.SWRST = 1;
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while (regs_->SYNCBUSY.reg) {
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}
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regs_->CTRLA.reg = SERCOM_I2CS_CTRLA_MODE_I2C_SLAVE;
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regs_->CTRLB.reg = SERCOM_I2CS_CTRLB_SMEN;
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regs_->ADDR.reg = SERCOM_I2CS_ADDR_ADDR(0x22);
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while (regs_->SYNCBUSY.reg) {
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}
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regs_->CTRLA.bit.ENABLE = 1;
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}
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void I2C::poll() {
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uint32_t flags = regs_->INTFLAG.reg;
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if (flags & SERCOM_I2CS_INTFLAG_PREC) {
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regs_->INTFLAG.reg = SERCOM_I2CS_INTFLAG_PREC;
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// STOP received.
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if (!read_) {
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received(input_buf_, output_buf_);
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}
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have_command_ = false;
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}
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if (flags & SERCOM_I2CS_INTFLAG_AMATCH) {
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regs_->INTFLAG.reg = SERCOM_I2CS_INTFLAG_AMATCH;
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at_ = 0;
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read_ = regs_->STATUS.bit.DIR;
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}
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if (flags & SERCOM_I2CS_INTFLAG_DRDY) {
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// Flag is cleared by hardware when DATA is read or written.
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if (!read_) {
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uint8_t data = regs_->DATA.reg;
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if (!have_command_) {
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if (data == kCommand) {
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have_command_ = true;
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ok_ = true;
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}
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} else if (have_command_ && at_ < sizeof(input_buf_)) {
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input_buf_[at_++] = data;
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} else {
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// Overflow or bad command, discard.
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}
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} else {
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if (have_command_ && at_ < sizeof(output_buf_)) {
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regs_->DATA.reg = output_buf_[at_++];
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} else {
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regs_->DATA.reg = 0;
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}
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}
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}
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}
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