remoteproc/mediatek: add SCP support for mt8183

Provide a basic driver to control Cortex M4 co-processor

Signed-off-by: Erin Lo <erin.lo@mediatek.com>
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Link: https://lore.kernel.org/r/20191112110330.179649-3-pihsun@chromium.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

1 files changed, 218 insertions, 0 deletions

diff --git a/drivers/remoteproc/mtk_scp_ipi.c b/drivers/remoteproc/mtk_scp_ipi.c
new file mode 100644
index 000000000000..abdb7944368a
--- /dev/null
+++ b/drivers/remoteproc/mtk_scp_ipi.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2019 MediaTek Inc.
+
+#include <asm/barrier.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/remoteproc/mtk_scp.h>
+
+#include "mtk_common.h"
+
+/**
+ * scp_ipi_register() - register an ipi function
+ *
+ * @scp:	mtk_scp structure
+ * @id:		IPI ID
+ * @handler:	IPI handler
+ * @priv:	private data for IPI handler
+ *
+ * Register an ipi function to receive ipi interrupt from SCP.
+ *
+ * Returns 0 if ipi registers successfully, -error on error.
+ */
+int scp_ipi_register(struct mtk_scp *scp,
+		     u32 id,
+		     scp_ipi_handler_t handler,
+		     void *priv)
+{
+	if (!scp) {
+		dev_err(scp->dev, "scp device is not ready\n");
+		return -EPROBE_DEFER;
+	}
+
+	if (WARN_ON(id >= SCP_IPI_MAX) || WARN_ON(handler == NULL))
+		return -EINVAL;
+
+	scp_ipi_lock(scp, id);
+	scp->ipi_desc[id].handler = handler;
+	scp->ipi_desc[id].priv = priv;
+	scp_ipi_unlock(scp, id);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(scp_ipi_register);
+
+/**
+ * scp_ipi_unregister() - unregister an ipi function
+ *
+ * @scp:	mtk_scp structure
+ * @id:		IPI ID
+ *
+ * Unregister an ipi function to receive ipi interrupt from SCP.
+ */
+void scp_ipi_unregister(struct mtk_scp *scp, u32 id)
+{
+	if (!scp)
+		return;
+
+	if (WARN_ON(id >= SCP_IPI_MAX))
+		return;
+
+	scp_ipi_lock(scp, id);
+	scp->ipi_desc[id].handler = NULL;
+	scp->ipi_desc[id].priv = NULL;
+	scp_ipi_unlock(scp, id);
+}
+EXPORT_SYMBOL_GPL(scp_ipi_unregister);
+
+/*
+ * scp_memcpy_aligned() - Copy src to dst, where dst is in SCP SRAM region.
+ *
+ * @dst:	Pointer to the destination buffer, should be in SCP SRAM region.
+ * @src:	Pointer to the source buffer.
+ * @len:	Length of the source buffer to be copied.
+ *
+ * Since AP access of SCP SRAM don't support byte write, this always write a
+ * full word at a time, and may cause some extra bytes to be written at the
+ * beginning & ending of dst.
+ */
+void scp_memcpy_aligned(void __iomem *dst, const void *src, unsigned int len)
+{
+	void __iomem *ptr;
+	u32 val;
+	unsigned int i = 0, remain;
+
+	if (!IS_ALIGNED((unsigned long)dst, 4)) {
+		ptr = (void __iomem *)ALIGN_DOWN((unsigned long)dst, 4);
+		i = 4 - (dst - ptr);
+		val = readl_relaxed(ptr);
+		memcpy((u8 *)&val + (4 - i), src, i);
+		writel_relaxed(val, ptr);
+	}
+
+	__iowrite32_copy(dst + i, src + i, (len - i) / 4);
+	remain = (len - i) % 4;
+
+	if (remain > 0) {
+		val = readl_relaxed(dst + len - remain);
+		memcpy(&val, src + len - remain, remain);
+		writel_relaxed(val, dst + len - remain);
+	}
+}
+EXPORT_SYMBOL_GPL(scp_memcpy_aligned);
+
+/**
+ * scp_ipi_lock() - Lock before operations of an IPI ID
+ *
+ * @scp:	mtk_scp structure
+ * @id:		IPI ID
+ *
+ * Note: This should not be used by drivers other than mtk_scp.
+ */
+void scp_ipi_lock(struct mtk_scp *scp, u32 id)
+{
+	if (WARN_ON(id >= SCP_IPI_MAX))
+		return;
+	mutex_lock(&scp->ipi_desc[id].lock);
+}
+EXPORT_SYMBOL_GPL(scp_ipi_lock);
+
+/**
+ * scp_ipi_lock() - Unlock after operations of an IPI ID
+ *
+ * @scp:	mtk_scp structure
+ * @id:		IPI ID
+ *
+ * Note: This should not be used by drivers other than mtk_scp.
+ */
+void scp_ipi_unlock(struct mtk_scp *scp, u32 id)
+{
+	if (WARN_ON(id >= SCP_IPI_MAX))
+		return;
+	mutex_unlock(&scp->ipi_desc[id].lock);
+}
+EXPORT_SYMBOL_GPL(scp_ipi_unlock);
+
+/**
+ * scp_ipi_send() - send data from AP to scp.
+ *
+ * @scp:	mtk_scp structure
+ * @id:		IPI ID
+ * @buf:	the data buffer
+ * @len:	the data buffer length
+ * @wait:	number of msecs to wait for ack. 0 to skip waiting.
+ *
+ * This function is thread-safe. When this function returns,
+ * SCP has received the data and starts the processing.
+ * When the processing completes, IPI handler registered
+ * by scp_ipi_register will be called in interrupt context.
+ *
+ * Returns 0 if sending data successfully, -error on error.
+ **/
+int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
+		 unsigned int wait)
+{
+	struct mtk_share_obj __iomem *send_obj = scp->send_buf;
+	unsigned long timeout;
+	int ret;
+
+	if (WARN_ON(id <= SCP_IPI_INIT) || WARN_ON(id >= SCP_IPI_MAX) ||
+	    WARN_ON(len > sizeof(send_obj->share_buf)) || WARN_ON(!buf))
+		return -EINVAL;
+
+	mutex_lock(&scp->send_lock);
+
+	ret = clk_prepare_enable(scp->clk);
+	if (ret) {
+		dev_err(scp->dev, "failed to enable clock\n");
+		goto unlock_mutex;
+	}
+
+	 /* Wait until SCP receives the last command */
+	timeout = jiffies + msecs_to_jiffies(2000);
+	do {
+		if (time_after(jiffies, timeout)) {
+			dev_err(scp->dev, "%s: IPI timeout!\n", __func__);
+			ret = -ETIMEDOUT;
+			goto clock_disable;
+		}
+	} while (readl(scp->reg_base + MT8183_HOST_TO_SCP));
+
+	scp_memcpy_aligned(send_obj->share_buf, buf, len);
+
+	writel(len, &send_obj->len);
+	writel(id, &send_obj->id);
+
+	scp->ipi_id_ack[id] = false;
+	/* send the command to SCP */
+	writel(MT8183_HOST_IPC_INT_BIT, scp->reg_base + MT8183_HOST_TO_SCP);
+
+	if (wait) {
+		/* wait for SCP's ACK */
+		timeout = msecs_to_jiffies(wait);
+		ret = wait_event_timeout(scp->ack_wq,
+					 scp->ipi_id_ack[id],
+					 timeout);
+		scp->ipi_id_ack[id] = false;
+		if (WARN(!ret, "scp ipi %d ack time out !", id))
+			ret = -EIO;
+		else
+			ret = 0;
+	}
+
+clock_disable:
+	clk_disable_unprepare(scp->clk);
+unlock_mutex:
+	mutex_unlock(&scp->send_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(scp_ipi_send);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MediaTek scp IPI interface");