mailbox: introduce stm32-ipcc driver

On STM32 family, the IPCC peripheral allows the communication
between 2 processors offering doorbells mechanism.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>

drivers/mailbox/Kconfig

@@ -24,6 +24,13 @@ config TEGRA_HSP
 	  This enables support for the NVIDIA Tegra HSP Hw module, which
 	  implements doorbells, mailboxes, semaphores, and shared interrupts.
 
+config STM32_IPCC
+	bool "Enable STM32 IPCC controller support"
+	depends on DM_MAILBOX && ARCH_STM32MP
+	help
+	  This enables support for the STM32MP IPCC Hw module, which
+	  implements doorbells between 2 processors.
+
 config K3_SEC_PROXY
 	bool "Texas Instruments K3 Secure Proxy Driver"
 	depends on DM_MAILBOX && ARCH_K3

drivers/mailbox/Makefile

@@ -6,5 +6,6 @@
 obj-$(CONFIG_$(SPL_)DM_MAILBOX) += mailbox-uclass.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-mbox.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-mbox-test.o
+obj-$(CONFIG_STM32_IPCC) += stm32-ipcc.o
 obj-$(CONFIG_TEGRA_HSP) += tegra-hsp.o
 obj-$(CONFIG_K3_SEC_PROXY) += k3-sec-proxy.o

drivers/mailbox/stm32-ipcc.c

@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2019 - All Rights Reserved
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <mailbox-uclass.h>
+#include <asm/io.h>
+
+/*
+ * IPCC has one set of registers per CPU
+ * IPCC_PROC_OFFST allows to define cpu registers set base address
+ * according to the assigned proc_id.
+ */
+
+#define IPCC_PROC_OFFST		0x010
+
+#define IPCC_XSCR		0x008
+#define IPCC_XTOYSR		0x00c
+
+#define IPCC_HWCFGR		0x3f0
+#define IPCFGR_CHAN_MASK	GENMASK(7, 0)
+
+#define RX_BIT_CHAN(chan)	BIT(chan)
+#define TX_BIT_SHIFT		16
+#define TX_BIT_CHAN(chan)	BIT(TX_BIT_SHIFT + (chan))
+
+#define STM32_MAX_PROCS		2
+
+struct stm32_ipcc {
+	void __iomem *reg_base;
+	void __iomem *reg_proc;
+	u32 proc_id;
+	u32 n_chans;
+};
+
+static int stm32_ipcc_request(struct mbox_chan *chan)
+{
+	struct stm32_ipcc *ipcc = dev_get_priv(chan->dev);
+
+	debug("%s(chan=%p)\n", __func__, chan);
+
+	if (chan->id >= ipcc->n_chans) {
+		debug("%s failed to request channel: %ld\n",
+		      __func__, chan->id);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int stm32_ipcc_free(struct mbox_chan *chan)
+{
+	debug("%s(chan=%p)\n", __func__, chan);
+
+	return 0;
+}
+
+static int stm32_ipcc_send(struct mbox_chan *chan, const void *data)
+{
+	struct stm32_ipcc *ipcc = dev_get_priv(chan->dev);
+
+	debug("%s(chan=%p, data=%p)\n", __func__, chan, data);
+
+	if (readl(ipcc->reg_proc + IPCC_XTOYSR) & BIT(chan->id))
+		return -EBUSY;
+
+	/* set channel n occupied */
+	setbits_le32(ipcc->reg_proc + IPCC_XSCR, TX_BIT_CHAN(chan->id));
+
+	return 0;
+}
+
+static int stm32_ipcc_recv(struct mbox_chan *chan, void *data)
+{
+	struct stm32_ipcc *ipcc = dev_get_priv(chan->dev);
+	u32 val;
+	int proc_offset;
+
+	debug("%s(chan=%p, data=%p)\n", __func__, chan, data);
+
+	/* read 'channel occupied' status from other proc */
+	proc_offset = ipcc->proc_id ? -IPCC_PROC_OFFST : IPCC_PROC_OFFST;
+	val = readl(ipcc->reg_proc + proc_offset + IPCC_XTOYSR);
+
+	if (!(val & BIT(chan->id)))
+		return -ENODATA;
+
+	setbits_le32(ipcc->reg_proc + IPCC_XSCR, RX_BIT_CHAN(chan->id));
+
+	return 0;
+}
+
+static int stm32_ipcc_probe(struct udevice *dev)
+{
+	struct stm32_ipcc *ipcc = dev_get_priv(dev);
+	fdt_addr_t addr;
+	const fdt32_t *cell;
+	struct clk clk;
+	int len, ret;
+
+	debug("%s(dev=%p)\n", __func__, dev);
+
+	addr = dev_read_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	ipcc->reg_base = (void __iomem *)addr;
+
+	/* proc_id */
+	cell = dev_read_prop(dev, "st,proc_id", &len);
+	if (len < sizeof(fdt32_t)) {
+		dev_dbg(dev, "Missing st,proc_id\n");
+		return -EINVAL;
+	}
+
+	ipcc->proc_id = fdtdec_get_number(cell, 1);
+
+	if (ipcc->proc_id >= STM32_MAX_PROCS) {
+		dev_err(dev, "Invalid proc_id (%d)\n", ipcc->proc_id);
+		return -EINVAL;
+	}
+
+	ipcc->reg_proc = ipcc->reg_base + ipcc->proc_id * IPCC_PROC_OFFST;
+
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable(&clk);
+	if (ret)
+		goto clk_free;
+
+	/* get channel number */
+	ipcc->n_chans = readl(ipcc->reg_base + IPCC_HWCFGR);
+	ipcc->n_chans &= IPCFGR_CHAN_MASK;
+
+	return 0;
+
+clk_free:
+	clk_free(&clk);
+
+	return ret;
+}
+
+static const struct udevice_id stm32_ipcc_ids[] = {
+	{ .compatible = "st,stm32mp1-ipcc" },
+	{ }
+};
+
+struct mbox_ops stm32_ipcc_mbox_ops = {
+	.request = stm32_ipcc_request,
+	.free = stm32_ipcc_free,
+	.send = stm32_ipcc_send,
+	.recv = stm32_ipcc_recv,
+};
+
+U_BOOT_DRIVER(stm32_ipcc) = {
+	.name = "stm32_ipcc",
+	.id = UCLASS_MAILBOX,
+	.of_match = stm32_ipcc_ids,
+	.probe = stm32_ipcc_probe,
+	.priv_auto_alloc_size = sizeof(struct stm32_ipcc),
+	.ops = &stm32_ipcc_mbox_ops,
+};