1 files changed, 280 insertions, 0 deletions
diff --git a/drivers/mfd/stm32-timers.c b/drivers/mfd/stm32-timers.c
new file mode 100644
index 000000000..1adba6a46
--- /dev/null
+++ b/drivers/mfd/stm32-timers.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2016
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/mfd/stm32-timers.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+
+#define STM32_TIMERS_MAX_REGISTERS	0x3fc
+
+/* DIER register DMA enable bits */
+static const u32 stm32_timers_dier_dmaen[STM32_TIMERS_MAX_DMAS] = {
+	TIM_DIER_CC1DE,
+	TIM_DIER_CC2DE,
+	TIM_DIER_CC3DE,
+	TIM_DIER_CC4DE,
+	TIM_DIER_UIE,
+	TIM_DIER_TDE,
+	TIM_DIER_COMDE
+};
+
+static void stm32_timers_dma_done(void *p)
+{
+	struct stm32_timers_dma *dma = p;
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(dma->chan, dma->chan->cookie, &state);
+	if (status == DMA_COMPLETE)
+		complete(&dma->completion);
+}
+
+/**
+ * stm32_timers_dma_burst_read - Read from timers registers using DMA.
+ *
+ * Read from STM32 timers registers using DMA on a single event.
+ * @dev: reference to stm32_timers MFD device
+ * @buf: DMA'able destination buffer
+ * @id: stm32_timers_dmas event identifier (ch[1..4], up, trig or com)
+ * @reg: registers start offset for DMA to read from (like CCRx for capture)
+ * @num_reg: number of registers to read upon each DMA request, starting @reg.
+ * @bursts: number of bursts to read (e.g. like two for pwm period capture)
+ * @tmo_ms: timeout (milliseconds)
+ */
+int stm32_timers_dma_burst_read(struct device *dev, u32 *buf,
+				enum stm32_timers_dmas id, u32 reg,
+				unsigned int num_reg, unsigned int bursts,
+				unsigned long tmo_ms)
+{
+	struct stm32_timers *ddata = dev_get_drvdata(dev);
+	unsigned long timeout = msecs_to_jiffies(tmo_ms);
+	struct regmap *regmap = ddata->regmap;
+	struct stm32_timers_dma *dma = &ddata->dma;
+	size_t len = num_reg * bursts * sizeof(u32);
+	struct dma_async_tx_descriptor *desc;
+	struct dma_slave_config config;
+	dma_cookie_t cookie;
+	dma_addr_t dma_buf;
+	u32 dbl, dba;
+	long err;
+	int ret;
+
+	/* Sanity check */
+	if (id < STM32_TIMERS_DMA_CH1 || id >= STM32_TIMERS_MAX_DMAS)
+		return -EINVAL;
+
+	if (!num_reg || !bursts || reg > STM32_TIMERS_MAX_REGISTERS ||
+	    (reg + num_reg * sizeof(u32)) > STM32_TIMERS_MAX_REGISTERS)
+		return -EINVAL;
+
+	if (!dma->chans[id])
+		return -ENODEV;
+	mutex_lock(&dma->lock);
+
+	/* Select DMA channel in use */
+	dma->chan = dma->chans[id];
+	dma_buf = dma_map_single(dev, buf, len, DMA_FROM_DEVICE);
+	if (dma_mapping_error(dev, dma_buf)) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	/* Prepare DMA read from timer registers, using DMA burst mode */
+	memset(&config, 0, sizeof(config));
+	config.src_addr = (dma_addr_t)dma->phys_base + TIM_DMAR;
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	ret = dmaengine_slave_config(dma->chan, &config);
+	if (ret)
+		goto unmap;
+
+	desc = dmaengine_prep_slave_single(dma->chan, dma_buf, len,
+					   DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+	if (!desc) {
+		ret = -EBUSY;
+		goto unmap;
+	}
+
+	desc->callback = stm32_timers_dma_done;
+	desc->callback_param = dma;
+	cookie = dmaengine_submit(desc);
+	ret = dma_submit_error(cookie);
+	if (ret)
+		goto dma_term;
+
+	reinit_completion(&dma->completion);
+	dma_async_issue_pending(dma->chan);
+
+	/* Setup and enable timer DMA burst mode */
+	dbl = FIELD_PREP(TIM_DCR_DBL, bursts - 1);
+	dba = FIELD_PREP(TIM_DCR_DBA, reg >> 2);
+	ret = regmap_write(regmap, TIM_DCR, dbl | dba);
+	if (ret)
+		goto dma_term;
+
+	/* Clear pending flags before enabling DMA request */
+	ret = regmap_write(regmap, TIM_SR, 0);
+	if (ret)
+		goto dcr_clr;
+
+	ret = regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id],
+				 stm32_timers_dier_dmaen[id]);
+	if (ret)
+		goto dcr_clr;
+
+	err = wait_for_completion_interruptible_timeout(&dma->completion,
+							timeout);
+	if (err == 0)
+		ret = -ETIMEDOUT;
+	else if (err < 0)
+		ret = err;
+
+	regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id], 0);
+	regmap_write(regmap, TIM_SR, 0);
+dcr_clr:
+	regmap_write(regmap, TIM_DCR, 0);
+dma_term:
+	dmaengine_terminate_all(dma->chan);
+unmap:
+	dma_unmap_single(dev, dma_buf, len, DMA_FROM_DEVICE);
+unlock:
+	dma->chan = NULL;
+	mutex_unlock(&dma->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(stm32_timers_dma_burst_read);
+
+static const struct regmap_config stm32_timers_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = STM32_TIMERS_MAX_REGISTERS,
+};
+
+static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
+{
+	u32 arr;
+
+	/* Backup ARR to restore it after getting the maximum value */
+	regmap_read(ddata->regmap, TIM_ARR, &arr);
+
+	/*
+	 * Only the available bits will be written so when readback
+	 * we get the maximum value of auto reload register
+	 */
+	regmap_write(ddata->regmap, TIM_ARR, ~0L);
+	regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr);
+	regmap_write(ddata->regmap, TIM_ARR, arr);
+}
+
+static void stm32_timers_dma_probe(struct device *dev,
+				   struct stm32_timers *ddata)
+{
+	int i;
+	char name[4];
+
+	init_completion(&ddata->dma.completion);
+	mutex_init(&ddata->dma.lock);
+
+	/* Optional DMA support: get valid DMA channel(s) or NULL */
+	for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
+		snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
+		ddata->dma.chans[i] = dma_request_slave_channel(dev, name);
+	}
+	ddata->dma.chans[STM32_TIMERS_DMA_UP] =
+		dma_request_slave_channel(dev, "up");
+	ddata->dma.chans[STM32_TIMERS_DMA_TRIG] =
+		dma_request_slave_channel(dev, "trig");
+	ddata->dma.chans[STM32_TIMERS_DMA_COM] =
+		dma_request_slave_channel(dev, "com");
+}
+
+static void stm32_timers_dma_remove(struct device *dev,
+				    struct stm32_timers *ddata)
+{
+	int i;
+
+	for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++)
+		if (ddata->dma.chans[i])
+			dma_release_channel(ddata->dma.chans[i]);
+}
+
+static int stm32_timers_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct stm32_timers *ddata;
+	struct resource *res;
+	void __iomem *mmio;
+	int ret;
+
+	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mmio = devm_ioremap_resource(dev, res);
+	if (IS_ERR(mmio))
+		return PTR_ERR(mmio);
+
+	/* Timer physical addr for DMA */
+	ddata->dma.phys_base = res->start;
+
+	ddata->regmap = devm_regmap_init_mmio_clk(dev, "int", mmio,
+						  &stm32_timers_regmap_cfg);
+	if (IS_ERR(ddata->regmap))
+		return PTR_ERR(ddata->regmap);
+
+	ddata->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ddata->clk))
+		return PTR_ERR(ddata->clk);
+
+	stm32_timers_get_arr_size(ddata);
+
+	stm32_timers_dma_probe(dev, ddata);
+
+	platform_set_drvdata(pdev, ddata);
+
+	ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+	if (ret)
+		stm32_timers_dma_remove(dev, ddata);
+
+	return ret;
+}
+
+static int stm32_timers_remove(struct platform_device *pdev)
+{
+	struct stm32_timers *ddata = platform_get_drvdata(pdev);
+
+	/*
+	 * Don't use devm_ here: enfore of_platform_depopulate() happens before
+	 * DMA are released, to avoid race on DMA.
+	 */
+	of_platform_depopulate(&pdev->dev);
+	stm32_timers_dma_remove(&pdev->dev, ddata);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_timers_of_match[] = {
+	{ .compatible = "st,stm32-timers", },
+	{ /* end node */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_timers_of_match);
+
+static struct platform_driver stm32_timers_driver = {
+	.probe = stm32_timers_probe,
+	.remove = stm32_timers_remove,
+	.driver	= {
+		.name = "stm32-timers",
+		.of_match_table = stm32_timers_of_match,
+	},
+};
+module_platform_driver(stm32_timers_driver);
+
+MODULE_DESCRIPTION("STMicroelectronics STM32 Timers");
+MODULE_LICENSE("GPL v2");