cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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i2c-at91-slave.c (3571B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 *  i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)
      4 *
      5 *  Copyright (C) 2017 Juergen Fitschen <me@jue.yt>
      6 */
      7
      8#include <linux/err.h>
      9#include <linux/i2c.h>
     10#include <linux/interrupt.h>
     11#include <linux/pm_runtime.h>
     12
     13#include "i2c-at91.h"
     14
     15static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)
     16{
     17	struct at91_twi_dev *dev = dev_id;
     18	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
     19	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
     20	u8 value;
     21
     22	if (!irqstatus)
     23		return IRQ_NONE;
     24
     25	/* slave address has been detected on I2C bus */
     26	if (irqstatus & AT91_TWI_SVACC) {
     27		if (status & AT91_TWI_SVREAD) {
     28			i2c_slave_event(dev->slave,
     29					I2C_SLAVE_READ_REQUESTED, &value);
     30			writeb_relaxed(value, dev->base + AT91_TWI_THR);
     31			at91_twi_write(dev, AT91_TWI_IER,
     32				       AT91_TWI_TXRDY | AT91_TWI_EOSACC);
     33		} else {
     34			i2c_slave_event(dev->slave,
     35					I2C_SLAVE_WRITE_REQUESTED, &value);
     36			at91_twi_write(dev, AT91_TWI_IER,
     37				       AT91_TWI_RXRDY | AT91_TWI_EOSACC);
     38		}
     39		at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);
     40	}
     41
     42	/* byte transmitted to remote master */
     43	if (irqstatus & AT91_TWI_TXRDY) {
     44		i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);
     45		writeb_relaxed(value, dev->base + AT91_TWI_THR);
     46	}
     47
     48	/* byte received from remote master */
     49	if (irqstatus & AT91_TWI_RXRDY) {
     50		value = readb_relaxed(dev->base + AT91_TWI_RHR);
     51		i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
     52	}
     53
     54	/* master sent stop */
     55	if (irqstatus & AT91_TWI_EOSACC) {
     56		at91_twi_write(dev, AT91_TWI_IDR,
     57			       AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);
     58		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
     59		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &value);
     60	}
     61
     62	return IRQ_HANDLED;
     63}
     64
     65static int at91_reg_slave(struct i2c_client *slave)
     66{
     67	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
     68
     69	if (dev->slave)
     70		return -EBUSY;
     71
     72	if (slave->flags & I2C_CLIENT_TEN)
     73		return -EAFNOSUPPORT;
     74
     75	/* Make sure twi_clk doesn't get turned off! */
     76	pm_runtime_get_sync(dev->dev);
     77
     78	dev->slave = slave;
     79	dev->smr = AT91_TWI_SMR_SADR(slave->addr);
     80
     81	at91_init_twi_bus(dev);
     82	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
     83
     84	dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);
     85
     86	return 0;
     87}
     88
     89static int at91_unreg_slave(struct i2c_client *slave)
     90{
     91	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
     92
     93	WARN_ON(!dev->slave);
     94
     95	dev_info(dev->dev, "leaving slave mode\n");
     96
     97	dev->slave = NULL;
     98	dev->smr = 0;
     99
    100	at91_init_twi_bus(dev);
    101
    102	pm_runtime_put(dev->dev);
    103
    104	return 0;
    105}
    106
    107static u32 at91_twi_func(struct i2c_adapter *adapter)
    108{
    109	return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
    110		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
    111}
    112
    113static const struct i2c_algorithm at91_twi_algorithm_slave = {
    114	.reg_slave	= at91_reg_slave,
    115	.unreg_slave	= at91_unreg_slave,
    116	.functionality	= at91_twi_func,
    117};
    118
    119int at91_twi_probe_slave(struct platform_device *pdev,
    120			 u32 phy_addr, struct at91_twi_dev *dev)
    121{
    122	int rc;
    123
    124	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,
    125			      0, dev_name(dev->dev), dev);
    126	if (rc) {
    127		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
    128		return rc;
    129	}
    130
    131	dev->adapter.algo = &at91_twi_algorithm_slave;
    132
    133	return 0;
    134}
    135
    136void at91_init_twi_bus_slave(struct at91_twi_dev *dev)
    137{
    138	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);
    139	if (dev->slave_detected && dev->smr) {
    140		at91_twi_write(dev, AT91_TWI_SMR, dev->smr);
    141		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);
    142	}
    143}