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// SPDX-License-Identifier: GPL-2.0
/*
* STM32 CEC driver
* Copyright (C) STMicroelectronics SA 2017
*
*/
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <media/cec.h>
#define CEC_NAME "stm32-cec"
/* CEC registers */
#define CEC_CR 0x0000 /* Control Register */
#define CEC_CFGR 0x0004 /* ConFiGuration Register */
#define CEC_TXDR 0x0008 /* Rx data Register */
#define CEC_RXDR 0x000C /* Rx data Register */
#define CEC_ISR 0x0010 /* Interrupt and status Register */
#define CEC_IER 0x0014 /* Interrupt enable Register */
#define TXEOM BIT(2)
#define TXSOM BIT(1)
#define CECEN BIT(0)
#define LSTN BIT(31)
#define OAR GENMASK(30, 16)
#define SFTOP BIT(8)
#define BRDNOGEN BIT(7)
#define LBPEGEN BIT(6)
#define BREGEN BIT(5)
#define BRESTP BIT(4)
#define RXTOL BIT(3)
#define SFT GENMASK(2, 0)
#define FULL_CFG (LSTN | SFTOP | BRDNOGEN | LBPEGEN | BREGEN | BRESTP \
| RXTOL)
#define TXACKE BIT(12)
#define TXERR BIT(11)
#define TXUDR BIT(10)
#define TXEND BIT(9)
#define TXBR BIT(8)
#define ARBLST BIT(7)
#define RXACKE BIT(6)
#define RXOVR BIT(2)
#define RXEND BIT(1)
#define RXBR BIT(0)
#define ALL_TX_IT (TXEND | TXBR | TXACKE | TXERR | TXUDR | ARBLST)
#define ALL_RX_IT (RXEND | RXBR | RXACKE | RXOVR)
/*
* 400 ms is the time it takes for one 16 byte message to be
* transferred and 5 is the maximum number of retries. Add
* another 100 ms as a margin.
*/
#define CEC_XFER_TIMEOUT_MS (5 * 400 + 100)
struct stm32_cec {
struct cec_adapter *adap;
struct device *dev;
struct clk *clk_cec;
struct clk *clk_hdmi_cec;
struct reset_control *rstc;
struct regmap *regmap;
int irq;
u32 irq_status;
struct cec_msg rx_msg;
struct cec_msg tx_msg;
int tx_cnt;
};
static void cec_hw_init(struct stm32_cec *cec)
{
regmap_update_bits(cec->regmap, CEC_CR, TXEOM | TXSOM | CECEN, 0);
regmap_update_bits(cec->regmap, CEC_IER, ALL_TX_IT | ALL_RX_IT,
ALL_TX_IT | ALL_RX_IT);
regmap_update_bits(cec->regmap, CEC_CFGR, FULL_CFG, FULL_CFG);
}
static void stm32_tx_done(struct stm32_cec *cec, u32 status)
{
if (status & (TXERR | TXUDR)) {
cec_transmit_done(cec->adap, CEC_TX_STATUS_ERROR,
0, 0, 0, 1);
return;
}
if (status & ARBLST) {
cec_transmit_done(cec->adap, CEC_TX_STATUS_ARB_LOST,
1, 0, 0, 0);
return;
}
if (status & TXACKE) {
cec_transmit_done(cec->adap, CEC_TX_STATUS_NACK,
0, 1, 0, 0);
return;
}
if (cec->irq_status & TXBR) {
/* send next byte */
if (cec->tx_cnt < cec->tx_msg.len)
regmap_write(cec->regmap, CEC_TXDR,
cec->tx_msg.msg[cec->tx_cnt++]);
/* TXEOM is set to command transmission of the last byte */
if (cec->tx_cnt == cec->tx_msg.len)
regmap_update_bits(cec->regmap, CEC_CR, TXEOM, TXEOM);
}
if (cec->irq_status & TXEND)
cec_transmit_done(cec->adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
}
static void stm32_rx_done(struct stm32_cec *cec, u32 status)
{
if (cec->irq_status & (RXACKE | RXOVR)) {
cec->rx_msg.len = 0;
return;
}
if (cec->irq_status & RXBR) {
u32 val;
regmap_read(cec->regmap, CEC_RXDR, &val);
cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF;
}
if (cec->irq_status & RXEND) {
cec_received_msg(cec->adap, &cec->rx_msg);
cec->rx_msg.len = 0;
}
}
static irqreturn_t stm32_cec_irq_thread(int irq, void *arg)
{
struct stm32_cec *cec = arg;
if (cec->irq_status & ALL_TX_IT)
stm32_tx_done(cec, cec->irq_status);
if (cec->irq_status & ALL_RX_IT)
stm32_rx_done(cec, cec->irq_status);
cec->irq_status = 0;
return IRQ_HANDLED;
}
static irqreturn_t stm32_cec_irq_handler(int irq, void *arg)
{
struct stm32_cec *cec = arg;
regmap_read(cec->regmap, CEC_ISR, &cec->irq_status);
regmap_update_bits(cec->regmap, CEC_ISR,
ALL_TX_IT | ALL_RX_IT,
ALL_TX_IT | ALL_RX_IT);
return IRQ_WAKE_THREAD;
}
static int stm32_cec_adap_enable(struct cec_adapter *adap, bool enable)
{
struct stm32_cec *cec = adap->priv;
int ret = 0;
if (enable) {
ret = clk_enable(cec->clk_cec);
if (ret)
dev_err(cec->dev, "fail to enable cec clock\n");
clk_enable(cec->clk_hdmi_cec);
regmap_update_bits(cec->regmap, CEC_CR, CECEN, CECEN);
} else {
clk_disable(cec->clk_cec);
clk_disable(cec->clk_hdmi_cec);
regmap_update_bits(cec->regmap, CEC_CR, CECEN, 0);
}
return ret;
}
static int stm32_cec_adap_log_addr(struct cec_adapter *adap, u8 logical_addr)
{
struct stm32_cec *cec = adap->priv;
u32 oar = (1 << logical_addr) << 16;
u32 val;
/* Poll every 100µs the register CEC_CR to wait end of transmission */
regmap_read_poll_timeout(cec->regmap, CEC_CR, val, !(val & TXSOM),
100, CEC_XFER_TIMEOUT_MS * 1000);
regmap_update_bits(cec->regmap, CEC_CR, CECEN, 0);
if (logical_addr == CEC_LOG_ADDR_INVALID)
regmap_update_bits(cec->regmap, CEC_CFGR, OAR, 0);
else
regmap_update_bits(cec->regmap, CEC_CFGR, oar, oar);
regmap_update_bits(cec->regmap, CEC_CR, CECEN, CECEN);
return 0;
}
static int stm32_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
u32 signal_free_time, struct cec_msg *msg)
{
struct stm32_cec *cec = adap->priv;
/* Copy message */
cec->tx_msg = *msg;
cec->tx_cnt = 0;
/*
* If the CEC message consists of only one byte,
* TXEOM must be set before of TXSOM.
*/
if (cec->tx_msg.len == 1)
regmap_update_bits(cec->regmap, CEC_CR, TXEOM, TXEOM);
/* TXSOM is set to command transmission of the first byte */
regmap_update_bits(cec->regmap, CEC_CR, TXSOM, TXSOM);
/* Write the header (first byte of message) */
regmap_write(cec->regmap, CEC_TXDR, cec->tx_msg.msg[0]);
cec->tx_cnt++;
return 0;
}
static const struct cec_adap_ops stm32_cec_adap_ops = {
.adap_enable = stm32_cec_adap_enable,
.adap_log_addr = stm32_cec_adap_log_addr,
.adap_transmit = stm32_cec_adap_transmit,
};
static const struct regmap_config stm32_cec_regmap_cfg = {
.reg_bits = 32,
.val_bits = 32,
.reg_stride = sizeof(u32),
.max_register = 0x14,
.fast_io = true,
};
static int stm32_cec_probe(struct platform_device *pdev)
{
u32 caps = CEC_CAP_DEFAULTS | CEC_CAP_PHYS_ADDR | CEC_MODE_MONITOR_ALL;
struct resource *res;
struct stm32_cec *cec;
void __iomem *mmio;
int ret;
cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
if (!cec)
return -ENOMEM;
cec->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mmio = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(mmio))
return PTR_ERR(mmio);
cec->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "cec", mmio,
&stm32_cec_regmap_cfg);
if (IS_ERR(cec->regmap))
return PTR_ERR(cec->regmap);
cec->irq = platform_get_irq(pdev, 0);
if (cec->irq < 0)
return cec->irq;
ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
stm32_cec_irq_handler,
stm32_cec_irq_thread,
0,
pdev->name, cec);
if (ret)
return ret;
cec->clk_cec = devm_clk_get(&pdev->dev, "cec");
if (IS_ERR(cec->clk_cec)) {
dev_err(&pdev->dev, "Cannot get cec clock\n");
return PTR_ERR(cec->clk_cec);
}
ret = clk_prepare(cec->clk_cec);
if (ret) {
dev_err(&pdev->dev, "Unable to prepare cec clock\n");
return ret;
}
cec->clk_hdmi_cec = devm_clk_get(&pdev->dev, "hdmi-cec");
if (!IS_ERR(cec->clk_hdmi_cec)) {
ret = clk_prepare(cec->clk_hdmi_cec);
if (ret) {
dev_err(&pdev->dev, "Unable to prepare hdmi-cec clock\n");
return ret;
}
}
/*
* CEC_CAP_PHYS_ADDR caps should be removed when a cec notifier is
* available for example when a drm driver can provide edid
*/
cec->adap = cec_allocate_adapter(&stm32_cec_adap_ops, cec,
CEC_NAME, caps, CEC_MAX_LOG_ADDRS);
ret = PTR_ERR_OR_ZERO(cec->adap);
if (ret)
return ret;
ret = cec_register_adapter(cec->adap, &pdev->dev);
if (ret) {
cec_delete_adapter(cec->adap);
return ret;
}
cec_hw_init(cec);
platform_set_drvdata(pdev, cec);
return 0;
}
static int stm32_cec_remove(struct platform_device *pdev)
{
struct stm32_cec *cec = platform_get_drvdata(pdev);
clk_unprepare(cec->clk_cec);
clk_unprepare(cec->clk_hdmi_cec);
cec_unregister_adapter(cec->adap);
return 0;
}
static const struct of_device_id stm32_cec_of_match[] = {
{ .compatible = "st,stm32-cec" },
{ /* end node */ }
};
MODULE_DEVICE_TABLE(of, stm32_cec_of_match);
static struct platform_driver stm32_cec_driver = {
.probe = stm32_cec_probe,
.remove = stm32_cec_remove,
.driver = {
.name = CEC_NAME,
.of_match_table = stm32_cec_of_match,
},
};
module_platform_driver(stm32_cec_driver);
MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
MODULE_DESCRIPTION("STMicroelectronics STM32 Consumer Electronics Control");
MODULE_LICENSE("GPL v2");