2 files changed, 384 insertions, 0 deletions
diff --git a/drivers/media/cec/platform/stm32/Makefile b/drivers/media/cec/platform/stm32/Makefile
new file mode 100644
index 000000000..b7597a00b
--- /dev/null
+++ b/drivers/media/cec/platform/stm32/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_CEC_STM32) += stm32-cec.o
diff --git a/drivers/media/cec/platform/stm32/stm32-cec.c b/drivers/media/cec/platform/stm32/stm32-cec.c
new file mode 100644
index 000000000..40db7911b
--- /dev/null
+++ b/drivers/media/cec/platform/stm32/stm32-cec.c
@@ -0,0 +1,382 @@
+// 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 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;
+
+	mmio = devm_platform_ioremap_resource(pdev, 0);
+	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)) {
+		if (PTR_ERR(cec->clk_cec) != -EPROBE_DEFER)
+			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) &&
+	    PTR_ERR(cec->clk_hdmi_cec) == -EPROBE_DEFER) {
+		ret = -EPROBE_DEFER;
+		goto err_unprepare_cec_clk;
+	}
+
+	if (!IS_ERR(cec->clk_hdmi_cec)) {
+		ret = clk_prepare(cec->clk_hdmi_cec);
+		if (ret) {
+			dev_err(&pdev->dev, "Can't prepare hdmi-cec clock\n");
+			goto err_unprepare_cec_clk;
+		}
+	}
+
+	/*
+	 * 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)
+		goto err_unprepare_hdmi_cec_clk;
+
+	ret = cec_register_adapter(cec->adap, &pdev->dev);
+	if (ret)
+		goto err_delete_adapter;
+
+	cec_hw_init(cec);
+
+	platform_set_drvdata(pdev, cec);
+
+	return 0;
+
+err_delete_adapter:
+	cec_delete_adapter(cec->adap);
+
+err_unprepare_hdmi_cec_clk:
+	clk_unprepare(cec->clk_hdmi_cec);
+
+err_unprepare_cec_clk:
+	clk_unprepare(cec->clk_cec);
+	return ret;
+}
+
+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");