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Subject[PATCH v5 2/2] mailbox: sprd: Add Spreadtrum mailbox driver
Date
From: Baolin Wang <baolin.wang@unisoc.com>

The Spreadtrum mailbox controller supports 8 channels to communicate
with MCUs, and it contains 2 different parts: inbox and outbox, which
are used to send and receive messages by IRQ mode.

Signed-off-by: Baolin Wang <baolin.wang@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
---
Changes from v4:
- Implement flush() to make sure the message has been fetched by
remote.

Changes from v3:
- Save the id in mbox_chan.con_priv and remove the 'sprd_mbox_chan'

Changes from v2:
- None.

Changes from v1:
- None
---
drivers/mailbox/Kconfig | 8 +
drivers/mailbox/Makefile | 2 +
drivers/mailbox/sprd-mailbox.c | 361 +++++++++++++++++++++++++++++++++
3 files changed, 371 insertions(+)
create mode 100644 drivers/mailbox/sprd-mailbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 5a577a6734cf..e03f3fb5caed 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -236,4 +236,12 @@ config SUN6I_MSGBOX
various Allwinner SoCs. This mailbox is used for communication
between the application CPUs and the power management coprocessor.

+config SPRD_MBOX
+ tristate "Spreadtrum Mailbox"
+ depends on ARCH_SPRD || COMPILE_TEST
+ help
+ Mailbox driver implementation for the Spreadtrum platform. It is used
+ to send message between application processors and MCU. Say Y here if
+ you want to build the Spreatrum mailbox controller driver.
+
endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 2e4364ef5c47..9caf4ede6ce0 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -50,3 +50,5 @@ obj-$(CONFIG_MTK_CMDQ_MBOX) += mtk-cmdq-mailbox.o
obj-$(CONFIG_ZYNQMP_IPI_MBOX) += zynqmp-ipi-mailbox.o

obj-$(CONFIG_SUN6I_MSGBOX) += sun6i-msgbox.o
+
+obj-$(CONFIG_SPRD_MBOX) += sprd-mailbox.o
diff --git a/drivers/mailbox/sprd-mailbox.c b/drivers/mailbox/sprd-mailbox.c
new file mode 100644
index 000000000000..f6fab24ae8a9
--- /dev/null
+++ b/drivers/mailbox/sprd-mailbox.c
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Spreadtrum mailbox driver
+ *
+ * Copyright (c) 2020 Spreadtrum Communications Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+
+#define SPRD_MBOX_ID 0x0
+#define SPRD_MBOX_MSG_LOW 0x4
+#define SPRD_MBOX_MSG_HIGH 0x8
+#define SPRD_MBOX_TRIGGER 0xc
+#define SPRD_MBOX_FIFO_RST 0x10
+#define SPRD_MBOX_FIFO_STS 0x14
+#define SPRD_MBOX_IRQ_STS 0x18
+#define SPRD_MBOX_IRQ_MSK 0x1c
+#define SPRD_MBOX_LOCK 0x20
+#define SPRD_MBOX_FIFO_DEPTH 0x24
+
+/* Bit and mask definiation for inbox's SPRD_MBOX_FIFO_STS register */
+#define SPRD_INBOX_FIFO_DELIVER_MASK GENMASK(23, 16)
+#define SPRD_INBOX_FIFO_OVERLOW_MASK GENMASK(15, 8)
+#define SPRD_INBOX_FIFO_DELIVER_SHIFT 16
+#define SPRD_INBOX_FIFO_BUSY_MASK GENMASK(7, 0)
+
+/* Bit and mask definiation for SPRD_MBOX_IRQ_STS register */
+#define SPRD_MBOX_IRQ_CLR BIT(0)
+
+/* Bit and mask definiation for outbox's SPRD_MBOX_FIFO_STS register */
+#define SPRD_OUTBOX_FIFO_FULL BIT(0)
+#define SPRD_OUTBOX_FIFO_WR_SHIFT 16
+#define SPRD_OUTBOX_FIFO_RD_SHIFT 24
+#define SPRD_OUTBOX_FIFO_POS_MASK GENMASK(7, 0)
+
+/* Bit and mask definiation for inbox's SPRD_MBOX_IRQ_MSK register */
+#define SPRD_INBOX_FIFO_BLOCK_IRQ BIT(0)
+#define SPRD_INBOX_FIFO_OVERFLOW_IRQ BIT(1)
+#define SPRD_INBOX_FIFO_DELIVER_IRQ BIT(2)
+#define SPRD_INBOX_FIFO_IRQ_MASK GENMASK(2, 0)
+
+/* Bit and mask definiation for outbox's SPRD_MBOX_IRQ_MSK register */
+#define SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ BIT(0)
+#define SPRD_OUTBOX_FIFO_IRQ_MASK GENMASK(4, 0)
+
+#define SPRD_MBOX_CHAN_MAX 8
+
+struct sprd_mbox_priv {
+ struct mbox_controller mbox;
+ struct device *dev;
+ void __iomem *inbox_base;
+ void __iomem *outbox_base;
+ struct clk *clk;
+ u32 outbox_fifo_depth;
+
+ struct mbox_chan chan[SPRD_MBOX_CHAN_MAX];
+};
+
+static struct sprd_mbox_priv *to_sprd_mbox_priv(struct mbox_controller *mbox)
+{
+ return container_of(mbox, struct sprd_mbox_priv, mbox);
+}
+
+static u32 sprd_mbox_get_fifo_len(struct sprd_mbox_priv *priv, u32 fifo_sts)
+{
+ u32 wr_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_WR_SHIFT) &
+ SPRD_OUTBOX_FIFO_POS_MASK;
+ u32 rd_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_RD_SHIFT) &
+ SPRD_OUTBOX_FIFO_POS_MASK;
+ u32 fifo_len;
+
+ /*
+ * If the read pointer is equal with write pointer, which means the fifo
+ * is full or empty.
+ */
+ if (wr_pos == rd_pos) {
+ if (fifo_sts & SPRD_OUTBOX_FIFO_FULL)
+ fifo_len = priv->outbox_fifo_depth;
+ else
+ fifo_len = 0;
+ } else if (wr_pos > rd_pos) {
+ fifo_len = wr_pos - rd_pos;
+ } else {
+ fifo_len = priv->outbox_fifo_depth - rd_pos + wr_pos;
+ }
+
+ return fifo_len;
+}
+
+static irqreturn_t sprd_mbox_outbox_isr(int irq, void *data)
+{
+ struct sprd_mbox_priv *priv = data;
+ struct mbox_chan *chan;
+ u32 fifo_sts, fifo_len, msg[2];
+ int i, id;
+
+ fifo_sts = readl(priv->outbox_base + SPRD_MBOX_FIFO_STS);
+
+ fifo_len = sprd_mbox_get_fifo_len(priv, fifo_sts);
+ if (!fifo_len) {
+ dev_warn_ratelimited(priv->dev, "spurious outbox interrupt\n");
+ return IRQ_NONE;
+ }
+
+ for (i = 0; i < fifo_len; i++) {
+ msg[0] = readl(priv->outbox_base + SPRD_MBOX_MSG_LOW);
+ msg[1] = readl(priv->outbox_base + SPRD_MBOX_MSG_HIGH);
+ id = readl(priv->outbox_base + SPRD_MBOX_ID);
+
+ chan = &priv->chan[id];
+ mbox_chan_received_data(chan, (void *)msg);
+
+ /* Trigger to update outbox FIFO pointer */
+ writel(0x1, priv->outbox_base + SPRD_MBOX_TRIGGER);
+ }
+
+ /* Clear irq status after reading all message. */
+ writel(SPRD_MBOX_IRQ_CLR, priv->outbox_base + SPRD_MBOX_IRQ_STS);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
+{
+ struct sprd_mbox_priv *priv = data;
+ struct mbox_chan *chan;
+ u32 fifo_sts, send_sts, busy, id;
+
+ fifo_sts = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS);
+
+ /* Get the inbox data delivery status */
+ send_sts = (fifo_sts & SPRD_INBOX_FIFO_DELIVER_MASK) >>
+ SPRD_INBOX_FIFO_DELIVER_SHIFT;
+ if (!send_sts) {
+ dev_warn_ratelimited(priv->dev, "spurious inbox interrupt\n");
+ return IRQ_NONE;
+ }
+
+ while (send_sts) {
+ id = __ffs(send_sts);
+ send_sts &= (send_sts - 1);
+
+ chan = &priv->chan[id];
+
+ /*
+ * Check if the message was fetched by remote traget, if yes,
+ * that means the transmission has been completed.
+ */
+ busy = fifo_sts & SPRD_INBOX_FIFO_BUSY_MASK;
+ if (!(busy & BIT(id)))
+ mbox_chan_txdone(chan, 0);
+ }
+
+ /* Clear FIFO delivery and overflow status */
+ writel(fifo_sts &
+ (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
+ priv->inbox_base + SPRD_MBOX_FIFO_RST);
+
+ /* Clear irq status */
+ writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);
+
+ return IRQ_HANDLED;
+}
+
+static int sprd_mbox_send_data(struct mbox_chan *chan, void *msg)
+{
+ struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+ unsigned long id = (unsigned long)chan->con_priv;
+ u32 *data = msg;
+
+ /* Write data into inbox FIFO, and only support 8 bytes every time */
+ writel(data[0], priv->inbox_base + SPRD_MBOX_MSG_LOW);
+ writel(data[1], priv->inbox_base + SPRD_MBOX_MSG_HIGH);
+
+ /* Set target core id */
+ writel(id, priv->inbox_base + SPRD_MBOX_ID);
+
+ /* Trigger remote request */
+ writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);
+
+ return 0;
+}
+
+static int sprd_mbox_flush(struct mbox_chan *chan, unsigned long timeout)
+{
+ struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+ unsigned long id = (unsigned long)chan->con_priv;
+ u32 busy;
+
+ timeout = jiffies + msecs_to_jiffies(timeout);
+
+ while (time_before(jiffies, timeout)) {
+ busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
+ SPRD_INBOX_FIFO_BUSY_MASK;
+ if (!(busy & BIT(id))) {
+ mbox_chan_txdone(chan, 0);
+ return 0;
+ }
+
+ udelay(1);
+ }
+
+ return -ETIME;
+}
+
+static int sprd_mbox_startup(struct mbox_chan *chan)
+{
+ struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+ u32 val;
+
+ /* Select outbox FIFO mode and reset the outbox FIFO status */
+ writel(0x0, priv->outbox_base + SPRD_MBOX_FIFO_RST);
+
+ /* Enable inbox FIFO overflow and delivery interrupt */
+ val = readl(priv->inbox_base + SPRD_MBOX_IRQ_MSK);
+ val &= ~(SPRD_INBOX_FIFO_OVERFLOW_IRQ | SPRD_INBOX_FIFO_DELIVER_IRQ);
+ writel(val, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
+
+ /* Enable outbox FIFO not empty interrupt */
+ val = readl(priv->outbox_base + SPRD_MBOX_IRQ_MSK);
+ val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
+ writel(val, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
+
+ return 0;
+}
+
+static void sprd_mbox_shutdown(struct mbox_chan *chan)
+{
+ struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+
+ /* Disable inbox & outbox interrupt */
+ writel(SPRD_INBOX_FIFO_IRQ_MASK, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
+ writel(SPRD_OUTBOX_FIFO_IRQ_MASK, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
+}
+
+static const struct mbox_chan_ops sprd_mbox_ops = {
+ .send_data = sprd_mbox_send_data,
+ .flush = sprd_mbox_flush,
+ .startup = sprd_mbox_startup,
+ .shutdown = sprd_mbox_shutdown,
+};
+
+static void sprd_mbox_disable(void *data)
+{
+ struct sprd_mbox_priv *priv = data;
+
+ clk_disable_unprepare(priv->clk);
+}
+
+static int sprd_mbox_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct sprd_mbox_priv *priv;
+ int ret, inbox_irq, outbox_irq;
+ unsigned long id;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->dev = dev;
+
+ /*
+ * The Spreadtrum mailbox uses an inbox to send messages to the target
+ * core, and uses an outbox to receive messages from other cores.
+ *
+ * Thus the mailbox controller supplies 2 different register addresses
+ * and IRQ numbers for inbox and outbox.
+ */
+ priv->inbox_base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->inbox_base))
+ return PTR_ERR(priv->inbox_base);
+
+ priv->outbox_base = devm_platform_ioremap_resource(pdev, 1);
+ if (IS_ERR(priv->outbox_base))
+ return PTR_ERR(priv->outbox_base);
+
+ priv->clk = devm_clk_get(dev, "enable");
+ if (IS_ERR(priv->clk)) {
+ dev_err(dev, "failed to get mailbox clock\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ ret = clk_prepare_enable(priv->clk);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
+ if (ret) {
+ dev_err(dev, "failed to add mailbox disable action\n");
+ return ret;
+ }
+
+ inbox_irq = platform_get_irq(pdev, 0);
+ if (inbox_irq < 0)
+ return inbox_irq;
+
+ ret = devm_request_irq(dev, inbox_irq, sprd_mbox_inbox_isr,
+ IRQF_NO_SUSPEND, dev_name(dev), priv);
+ if (ret) {
+ dev_err(dev, "failed to request inbox IRQ: %d\n", ret);
+ return ret;
+ }
+
+ outbox_irq = platform_get_irq(pdev, 1);
+ if (outbox_irq < 0)
+ return outbox_irq;
+
+ ret = devm_request_irq(dev, outbox_irq, sprd_mbox_outbox_isr,
+ IRQF_NO_SUSPEND, dev_name(dev), priv);
+ if (ret) {
+ dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
+ return ret;
+ }
+
+ /* Get the default outbox FIFO depth */
+ priv->outbox_fifo_depth =
+ readl(priv->outbox_base + SPRD_MBOX_FIFO_DEPTH) + 1;
+ priv->mbox.dev = dev;
+ priv->mbox.chans = &priv->chan[0];
+ priv->mbox.num_chans = SPRD_MBOX_CHAN_MAX;
+ priv->mbox.ops = &sprd_mbox_ops;
+ priv->mbox.txdone_irq = true;
+
+ for (id = 0; id < SPRD_MBOX_CHAN_MAX; id++)
+ priv->chan[id].con_priv = (void *)id;
+
+ ret = devm_mbox_controller_register(dev, &priv->mbox);
+ if (ret) {
+ dev_err(dev, "failed to register mailbox: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id sprd_mbox_of_match[] = {
+ { .compatible = "sprd,sc9860-mailbox", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, sprd_mbox_of_match);
+
+static struct platform_driver sprd_mbox_driver = {
+ .driver = {
+ .name = "sprd-mailbox",
+ .of_match_table = sprd_mbox_of_match,
+ },
+ .probe = sprd_mbox_probe,
+};
+module_platform_driver(sprd_mbox_driver);
+
+MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
+MODULE_DESCRIPTION("Spreadtrum mailbox driver");
+MODULE_LICENSE("GPL v2");
--
2.17.1
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