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SubjectRe: [PATCH v13 2/5] remoteproc/mediatek: add SCP support for mt8183
Hi Pi-Hsun,

On Tue, Jul 9, 2019 at 4:27 PM Pi-Hsun Shih <pihsun@chromium.org> wrote:
>
> From: Erin Lo <erin.lo@mediatek.com>
>
> 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>
> ---
> Changes from v12:
> - Initialize cache before firmware load, to avoid problem while loading
> large firmware.
> - Disable watchdog before stopping SCP, to avoid extra warning message.
> - Use strscpy instead of strncpy.
>
> Changes from v11:
> - No change.
>
> Changes from v10:
> - Add a clock reset before loading firmware.
>
> Changes from v9:
> - No change.
>
> Changes from v8:
> - Add a missing space.
>
> Changes from v7:
> - Moved the location of shared SCP buffer.
> - Fix clock enable/disable sequence.
> - Add more IPI ID that would be used.
>
> Changes from v6:
> - No change.
>
> Changes from v5:
> - Changed some space to tab.
>
> Changes from v4:
> - Rename most function from mtk_scp_* to scp_*.
> - Change the irq to threaded handler.
> - Load ELF file instead of plain binary file as firmware by default
> (Squashed patch 6 in v4 into this patch).
>
> Changes from v3:
> - Fix some issue found by checkpatch.
> - Make writes aligned in scp_ipi_send.
>
> Changes from v2:
> - Squash patch 3 from v2 (separate the ipi interface) into this patch.
> - Remove unused name argument from scp_ipi_register.
> - Add scp_ipi_unregister for proper cleanup.
> - Move IPI ids in sync with firmware.
> - Add mb() in proper place, and correctly clear the run->signaled.
>
> Changes from v1:
> - Extract functions and rename variables in mtk_scp.c.
> ---
> drivers/remoteproc/Kconfig | 9 +
> drivers/remoteproc/Makefile | 1 +
> drivers/remoteproc/mtk_common.h | 80 ++++
> drivers/remoteproc/mtk_scp.c | 523 ++++++++++++++++++++++++++
> drivers/remoteproc/mtk_scp_ipi.c | 162 ++++++++
> include/linux/platform_data/mtk_scp.h | 141 +++++++
> 6 files changed, 916 insertions(+)
> create mode 100644 drivers/remoteproc/mtk_common.h
> create mode 100644 drivers/remoteproc/mtk_scp.c
> create mode 100644 drivers/remoteproc/mtk_scp_ipi.c
> create mode 100644 include/linux/platform_data/mtk_scp.h
>
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index 28ed306982f7..ea71cad399f7 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -23,6 +23,15 @@ config IMX_REMOTEPROC
>
> It's safe to say N here.
>
> +config MTK_SCP
> + tristate "Mediatek SCP support"
> + depends on ARCH_MEDIATEK
> + help
> + Say y here to support Mediatek's System Companion Processor (SCP) via
> + the remote processor framework.
> +
> + It's safe to say N here.
> +
> config OMAP_REMOTEPROC
> tristate "OMAP remoteproc support"
> depends on ARCH_OMAP4 || SOC_OMAP5
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 00f09e658cb3..e30a1b15fbac 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -10,6 +10,7 @@ remoteproc-y += remoteproc_sysfs.o
> remoteproc-y += remoteproc_virtio.o
> remoteproc-y += remoteproc_elf_loader.o
> obj-$(CONFIG_IMX_REMOTEPROC) += imx_rproc.o
> +obj-$(CONFIG_MTK_SCP) += mtk_scp.o mtk_scp_ipi.o
> obj-$(CONFIG_OMAP_REMOTEPROC) += omap_remoteproc.o
> obj-$(CONFIG_WKUP_M3_RPROC) += wkup_m3_rproc.o
> obj-$(CONFIG_DA8XX_REMOTEPROC) += da8xx_remoteproc.o
> diff --git a/drivers/remoteproc/mtk_common.h b/drivers/remoteproc/mtk_common.h
> new file mode 100644
> index 000000000000..df918525da92
> --- /dev/null
> +++ b/drivers/remoteproc/mtk_common.h
> @@ -0,0 +1,80 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2018 MediaTek Inc.

This should probably say 2019 now.

> + */
> +
> +#ifndef __RPROC_MTK_COMMON_H
> +#define __RPROC_MTK_COMMON_H
> +
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +
> +#define MT8183_SW_RSTN 0x0
> +#define MT8183_SW_RSTN_BIT BIT(0)
> +#define MT8183_SCP_TO_HOST 0x1C
> +#define MT8183_SCP_IPC_INT_BIT BIT(0)
> +#define MT8183_SCP_WDT_INT_BIT BIT(8)
> +#define MT8183_HOST_TO_SCP 0x28
> +#define MT8183_HOST_IPC_INT_BIT BIT(0)
> +#define MT8183_WDT_CFG 0x84
> +#define MT8183_SCP_CLK_SW_SEL 0x4000
> +#define MT8183_SCP_CLK_DIV_SEL 0x4024
> +#define MT8183_SCP_SRAM_PDN 0x402C
> +#define MT8183_SCP_L1_SRAM_PD 0x4080
> +#define MT8183_SCP_TCM_TAIL_SRAM_PD 0x4094
> +
> +#define SCP_FW_VER_LEN 32
> +
> +struct scp_run {
> + u32 signaled;
> + s8 fw_ver[SCP_FW_VER_LEN];
> + u32 dec_capability;
> + u32 enc_capability;
> + wait_queue_head_t wq;
> +};
> +
> +struct scp_ipi_desc {
> + scp_ipi_handler_t handler;
> + void *priv;
> +};
> +
> +struct mtk_scp {
> + struct device *dev;
> + struct rproc *rproc;
> + struct clk *clk;
> + void __iomem *reg_base;
> + void __iomem *sram_base;
> + size_t sram_size;
> +
> + struct share_obj *recv_buf;
> + struct share_obj *send_buf;
> + struct scp_run run;
> + struct mutex lock; /* for protecting mtk_scp data structure */

The comment does not really help fine-tuning the scope of this lock.
Does it protect the *whole* structure? Or which members exactly?

I only see this lock being acquired in scp_ipi_send(). But shouldn't
we also protect against concurrent access in e.g. the interrupt
handler?

> + struct scp_ipi_desc ipi_desc[SCP_IPI_MAX];
> + bool ipi_id_ack[SCP_IPI_MAX];
> + wait_queue_head_t ack_wq;
> +
> + void __iomem *cpu_addr;
> + phys_addr_t phys_addr;
> + size_t dram_size;
> +};
> +
> +/**
> + * struct share_obj - SRAM buffer shared with
> + * AP and SCP
> + *
> + * @id: IPI id
> + * @len: share buffer length
> + * @share_buf: share buffer data
> + */
> +struct share_obj {
> + s32 id;
> + u32 len;
> + u8 share_buf[288];
> +};
> +
> +void scp_memcpy_aligned(void *dst, const void *src, unsigned int len);
> +
> +#endif
> diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> new file mode 100644
> index 000000000000..4713574d1aa2
> --- /dev/null
> +++ b/drivers/remoteproc/mtk_scp.c
> @@ -0,0 +1,523 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Copyright (c) 2018 MediaTek Inc.
> +
> +#include <asm/barrier.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_data/mtk_scp.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +
> +#include "mtk_common.h"
> +#include "remoteproc_internal.h"
> +
> +#define MAX_CODE_SIZE 0x500000
> +#define SCP_FW_END 0x7C000
> +
> +struct platform_device *scp_get_pdev(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *scp_node;
> + struct platform_device *scp_pdev;
> +
> + scp_node = of_parse_phandle(dev->of_node, "mediatek,scp", 0);
> + if (!scp_node) {
> + dev_err(dev, "can't get SCP node\n");
> + return NULL;
> + }
> +
> + scp_pdev = of_find_device_by_node(scp_node);
> + if (WARN_ON(!scp_pdev)) {
> + dev_err(dev, "SCP pdev failed\n");
> + of_node_put(scp_node);
> + return NULL;
> + }
> +
> + return scp_pdev;
> +}
> +EXPORT_SYMBOL_GPL(scp_get_pdev);
> +
> +static void scp_wdt_handler(struct mtk_scp *scp)
> +{
> + rproc_report_crash(scp->rproc, RPROC_WATCHDOG);
> +}
> +
> +static void scp_init_ipi_handler(void *data, unsigned int len, void *priv)
> +{
> + struct mtk_scp *scp = (struct mtk_scp *)priv;
> + struct scp_run *run = (struct scp_run *)data;
> +
> + scp->run.signaled = run->signaled;
> + strscpy(scp->run.fw_ver, run->fw_ver, SCP_FW_VER_LEN);
> + scp->run.dec_capability = run->dec_capability;
> + scp->run.enc_capability = run->enc_capability;
> + wake_up_interruptible(&scp->run.wq);
> +}
> +
> +static void scp_ipi_handler(struct mtk_scp *scp)
> +{
> + struct share_obj *rcv_obj = scp->recv_buf;
> + struct scp_ipi_desc *ipi_desc = scp->ipi_desc;
> + u8 tmp_data[288];

Since this is the same size as share_obj::share_buf, let's declare
this as "u8 tmp_data[sizeof(rcv_obj->share_buf)] or use a macro to
express this size.

> +
> + if (rcv_obj->id >= SCP_IPI_MAX || !ipi_desc[rcv_obj->id].handler) {

Technically rcv_obj->id can be < 0 since it is declared as s32. So we
need to check for that case, or maybe better turn it into a u32?

> + dev_err(scp->dev, "No such ipi id = %d\n", rcv_obj->id);
> + return;
> + }
> +
> + memcpy_fromio(tmp_data, &rcv_obj->share_buf, rcv_obj->len);

Maybe we should check that obj->len is not larger than our destination array?

> + ipi_desc[rcv_obj->id].handler(tmp_data,
> + rcv_obj->len,
> + ipi_desc[rcv_obj->id].priv);
> + scp->ipi_id_ack[rcv_obj->id] = true;
> + wake_up(&scp->ack_wq);
> +}
> +
> +static int scp_ipi_init(struct mtk_scp *scp)
> +{
> + size_t send_offset = SCP_FW_END - sizeof(struct share_obj);
> + size_t recv_offset = send_offset - sizeof(struct share_obj);
> +
> + /* Disable SCP to host interrupt */
> + writel(MT8183_SCP_IPC_INT_BIT, scp->reg_base + MT8183_SCP_TO_HOST);
> +
> + /* shared buffer initialization */
> + scp->recv_buf = (__force struct share_obj *)(scp->sram_base +
> + recv_offset);
> + scp->send_buf = (__force struct share_obj *)(scp->sram_base +
> + send_offset);
> + memset_io(scp->recv_buf, 0, sizeof(scp->recv_buf));
> + memset_io(scp->send_buf, 0, sizeof(scp->send_buf));
> +
> + return 0;
> +}
> +
> +static void scp_reset_assert(const struct mtk_scp *scp)
> +{
> + u32 val;
> +
> + val = readl(scp->reg_base + MT8183_SW_RSTN);
> + val &= ~MT8183_SW_RSTN_BIT;
> + writel(val, scp->reg_base + MT8183_SW_RSTN);
> +}
> +
> +static void scp_reset_deassert(const struct mtk_scp *scp)
> +{
> + u32 val;
> +
> + val = readl(scp->reg_base + MT8183_SW_RSTN);
> + val |= MT8183_SW_RSTN_BIT;
> + writel(val, scp->reg_base + MT8183_SW_RSTN);
> +}
> +
> +static irqreturn_t scp_irq_handler(int irq, void *priv)
> +{
> + struct mtk_scp *scp = priv;
> + u32 scp_to_host;
> + int ret;
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(scp->dev, "failed to enable clocks\n");
> + return IRQ_NONE;
> + }
> +
> + scp_to_host = readl(scp->reg_base + MT8183_SCP_TO_HOST);
> + if (scp_to_host & MT8183_SCP_IPC_INT_BIT) {
> + scp_ipi_handler(scp);
> + } else {
> + dev_err(scp->dev, "SCP watchdog timeout! 0x%x", scp_to_host);

IMHO this dev_err would be better placed in scp_wdt_handler(). In that
case it would also take scp_to_host as argument to properly display
it.

> + scp_wdt_handler(scp);
> + }
> +
> + /*
> + * Ensure that all writes to SRAM are committed before another
> + * interrupt.
> + */
> + mb();
> + /* SCP won't send another interrupt until we set SCP_TO_HOST to 0. */
> + writel(MT8183_SCP_IPC_INT_BIT | MT8183_SCP_WDT_INT_BIT,
> + scp->reg_base + MT8183_SCP_TO_HOST);
> + clk_disable_unprepare(scp->clk);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int scp_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
> +{
> + struct device *dev = &rproc->dev;
> + struct elf32_hdr *ehdr;
> + struct elf32_phdr *phdr;
> + int i, ret = 0;
> + const u8 *elf_data = fw->data;
> +
> + ehdr = (struct elf32_hdr *)elf_data;
> + phdr = (struct elf32_phdr *)(elf_data + ehdr->e_phoff);
> +
> + /* go through the available ELF segments */
> + for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
> + u32 da = phdr->p_paddr;
> + u32 memsz = phdr->p_memsz;
> + u32 filesz = phdr->p_filesz;
> + u32 offset = phdr->p_offset;
> + void __iomem *ptr;
> +
> + if (phdr->p_type != PT_LOAD)
> + continue;
> +
> + dev_dbg(dev, "phdr: type %d da 0x%x memsz 0x%x filesz 0x%x\n",
> + phdr->p_type, da, memsz, filesz);
> +
> + if (filesz > memsz) {
> + dev_err(dev, "bad phdr filesz 0x%x memsz 0x%x\n",
> + filesz, memsz);
> + ret = -EINVAL;
> + break;
> + }
> +
> + if (offset + filesz > fw->size) {
> + dev_err(dev, "truncated fw: need 0x%x avail 0x%zx\n",
> + offset + filesz, fw->size);
> + ret = -EINVAL;
> + break;
> + }
> +
> + /* grab the kernel address for this device address */
> + ptr = rproc_da_to_va(rproc, da, memsz);
> + if (!ptr) {
> + dev_err(dev, "bad phdr da 0x%x mem 0x%x\n", da, memsz);
> + ret = -EINVAL;
> + break;
> + }
> +
> + /* put the segment where the remote processor expects it */
> + if (phdr->p_filesz)
> + scp_memcpy_aligned(ptr, elf_data + phdr->p_offset,
> + filesz);
> + }
> +
> + return ret;
> +}
> +
> +static int scp_load(struct rproc *rproc, const struct firmware *fw)
> +{
> + const struct mtk_scp *scp = rproc->priv;
> + struct device *dev = scp->dev;
> + int ret;
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(dev, "failed to enable clocks\n");
> + return ret;
> + }
> +
> + /* Hold SCP in reset while loading FW. */
> + scp_reset_assert(scp);
> +
> + /* Reset clocks before loading FW */
> + writel(0x0, scp->reg_base + MT8183_SCP_CLK_SW_SEL);
> + writel(0x0, scp->reg_base + MT8183_SCP_CLK_DIV_SEL);
> +
> + /* Initialize TCM before loading FW. */
> + writel(0x0, scp->reg_base + MT8183_SCP_L1_SRAM_PD);
> + writel(0x0, scp->reg_base + MT8183_SCP_TCM_TAIL_SRAM_PD);
> +
> + /* Turn on the power of SCP's SRAM before using it. */
> + writel(0x0, scp->reg_base + MT8183_SCP_SRAM_PDN);
> + ret = scp_elf_load_segments(rproc, fw);
> + clk_disable_unprepare(scp->clk);
> +
> + return ret;
> +}
> +
> +static int scp_start(struct rproc *rproc)
> +{
> + struct mtk_scp *scp = (struct mtk_scp *)rproc->priv;
> + struct device *dev = scp->dev;
> + struct scp_run *run;
> + int ret;
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(dev, "failed to enable clocks\n");
> + return ret;
> + }
> +
> + run = &scp->run;

You can initialize run when declaring it.

> + run->signaled = false;
> +
> + scp_reset_deassert(scp);
> +
> + ret = wait_event_interruptible_timeout(
> + run->wq,
> + run->signaled,
> + msecs_to_jiffies(2000));
> +
> + if (ret == 0) {
> + dev_err(dev, "wait SCP initialization timeout!\n");
> + ret = -ETIME;
> + goto stop;
> + }
> + if (ret == -ERESTARTSYS) {
> + dev_err(dev, "wait SCP interrupted by a signal!\n");
> + goto stop;
> + }
> + clk_disable_unprepare(scp->clk);
> + dev_info(dev, "SCP is ready. FW version %s\n", run->fw_ver);
> +
> + return 0;
> +
> +stop:
> + scp_reset_assert(scp);
> + clk_disable_unprepare(scp->clk);
> + return ret;
> +}
> +
> +static void *scp_da_to_va(struct rproc *rproc, u64 da, int len)
> +{
> + struct mtk_scp *scp = (struct mtk_scp *)rproc->priv;
> + int offset;
> +
> + if (da < scp->sram_size) {
> + offset = da;
> + if (offset >= 0 && ((offset + len) < scp->sram_size))
> + return (__force void *)(scp->sram_base + offset);
> + } else if (da >= scp->sram_size &&
> + da < (scp->sram_size + MAX_CODE_SIZE)) {
> + offset = da;

This line looks suspicious. Shouldn't it be

offset = da - scp->sram_size?

> + if (offset >= 0 && (offset + len) < MAX_CODE_SIZE)
> + return scp->cpu_addr + offset;
> + } else {
> + offset = da - scp->phys_addr;
> + if (offset >= 0 &&
> + (offset + len) < (scp->dram_size - MAX_CODE_SIZE))
> + return scp->cpu_addr + offset;
> + }
> +
> + return NULL;
> +}
> +
> +static int scp_stop(struct rproc *rproc)
> +{
> + struct mtk_scp *scp = (struct mtk_scp *)rproc->priv;
> + int ret;
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(scp->dev, "failed to enable clocks\n");
> + return ret;
> + }
> +
> + scp_reset_assert(scp);
> + /* Disable SCP watchdog */
> + writel(0, scp->reg_base + MT8183_WDT_CFG);
> + clk_disable_unprepare(scp->clk);
> +
> + return 0;
> +}
> +
> +static const struct rproc_ops scp_ops = {
> + .start = scp_start,
> + .stop = scp_stop,
> + .load = scp_load,
> + .da_to_va = scp_da_to_va,
> +};
> +
> +unsigned int scp_get_vdec_hw_capa(struct platform_device *pdev)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> +
> + return scp->run.dec_capability;
> +}
> +EXPORT_SYMBOL_GPL(scp_get_vdec_hw_capa);
> +
> +unsigned int scp_get_venc_hw_capa(struct platform_device *pdev)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> +
> + return scp->run.enc_capability;
> +}
> +EXPORT_SYMBOL_GPL(scp_get_venc_hw_capa);
> +
> +void *scp_mapping_dm_addr(struct platform_device *pdev, u32 mem_addr)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> + void *ptr;
> +
> + ptr = scp_da_to_va(scp->rproc, mem_addr, 0);
> + if (!ptr)
> + return ERR_PTR(-EINVAL);
> +
> + return ptr;
> +}
> +EXPORT_SYMBOL_GPL(scp_mapping_dm_addr);
> +
> +static int scp_map_memory_region(struct mtk_scp *scp)
> +{
> + struct device_node *node;
> + struct resource r;
> + int ret;
> +
> + node = of_parse_phandle(scp->dev->of_node, "memory-region", 0);
> + if (!node) {
> + dev_err(scp->dev, "no memory-region specified\n");
> + return -EINVAL;
> + }
> +
> + ret = of_address_to_resource(node, 0, &r);
> + if (ret)
> + return ret;
> +
> + scp->phys_addr = r.start;
> + scp->dram_size = resource_size(&r);
> + scp->cpu_addr =
> + devm_ioremap_wc(scp->dev, scp->phys_addr, scp->dram_size);
> +
> + if (!scp->cpu_addr) {
> + dev_err(scp->dev, "unable to map memory region: %pa+%zx\n",
> + &r.start, scp->dram_size);
> + return -EBUSY;
> + }
> +
> + return 0;
> +}
> +
> +static int scp_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct mtk_scp *scp;
> + struct rproc *rproc;
> + struct resource *res;
> + char *fw_name = "scp.img";
> + int ret;
> +
> + rproc = rproc_alloc(dev,
> + np->name,
> + &scp_ops,
> + fw_name,
> + sizeof(*scp));
> + if (!rproc) {
> + dev_err(dev, "unable to allocate remoteproc\n");
> + return -ENOMEM;
> + }
> +
> + scp = (struct mtk_scp *)rproc->priv;
> + scp->rproc = rproc;
> + scp->dev = dev;
> + platform_set_drvdata(pdev, scp);
> +
> + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "sram");
> + scp->sram_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR((__force void *)scp->sram_base)) {
> + dev_err(dev, "Failed to parse and map sram memory\n");
> + ret = PTR_ERR((__force void *)scp->sram_base);
> + goto free_rproc;
> + }
> + scp->sram_size = resource_size(res);
> +
> + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
> + scp->reg_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR((__force void *)scp->reg_base)) {
> + dev_err(dev, "Failed to parse and map cfg memory\n");
> + ret = PTR_ERR((__force void *)scp->reg_base);
> + goto free_rproc;
> + }
> +
> + ret = scp_map_memory_region(scp);
> + if (ret)
> + goto free_rproc;
> +
> + scp->clk = devm_clk_get(dev, "main");
> + if (IS_ERR(scp->clk)) {
> + dev_err(dev, "Failed to get clock\n");
> + ret = PTR_ERR(scp->clk);
> + goto free_rproc;
> + }
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(dev, "failed to enable clocks\n");
> + goto free_rproc;
> + }
> +
> + ret = scp_ipi_init(scp);
> + clk_disable_unprepare(scp->clk);
> + if (ret) {
> + dev_err(dev, "Failed to init ipi\n");
> + goto free_rproc;
> + }
> +
> + /* register SCP initialization IPI */
> + ret = scp_ipi_register(pdev,
> + SCP_IPI_INIT,
> + scp_init_ipi_handler,
> + scp);
> + if (ret) {
> + dev_err(dev, "Failed to register IPI_SCP_INIT\n");
> + goto free_rproc;
> + }
> +
> + mutex_init(&scp->lock);
> +
> + init_waitqueue_head(&scp->run.wq);
> + init_waitqueue_head(&scp->ack_wq);
> +
> + ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0), NULL,
> + scp_irq_handler, IRQF_ONESHOT,
> + pdev->name, scp);
> +
> + if (ret) {
> + dev_err(dev, "failed to request irq\n");
> + goto destroy_mutex;
> + }
> +
> + ret = rproc_add(rproc);
> + if (ret)
> + goto destroy_mutex;
> +
> + return ret;
> +
> +destroy_mutex:
> + mutex_destroy(&scp->lock);
> +free_rproc:
> + rproc_free(rproc);
> +
> + return ret;
> +}
> +
> +static int scp_remove(struct platform_device *pdev)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> +
> + rproc_del(scp->rproc);
> + rproc_free(scp->rproc);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id mtk_scp_of_match[] = {
> + { .compatible = "mediatek,mt8183-scp"},
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, mtk_scp_of_match);
> +
> +static struct platform_driver mtk_scp_driver = {
> + .probe = scp_probe,
> + .remove = scp_remove,
> + .driver = {
> + .name = "mtk-scp",
> + .of_match_table = of_match_ptr(mtk_scp_of_match),
> + },
> +};
> +
> +module_platform_driver(mtk_scp_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MediaTek SCP control driver");
> diff --git a/drivers/remoteproc/mtk_scp_ipi.c b/drivers/remoteproc/mtk_scp_ipi.c
> new file mode 100644
> index 000000000000..f5d271c0f623
> --- /dev/null
> +++ b/drivers/remoteproc/mtk_scp_ipi.c
> @@ -0,0 +1,162 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Copyright (c) 2018 MediaTek Inc.
> +
> +#include <asm/barrier.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_data/mtk_scp.h>
> +#include <linux/platform_device.h>
> +
> +#include "mtk_common.h"
> +
> +int scp_ipi_register(struct platform_device *pdev,
> + enum scp_ipi_id id,
> + scp_ipi_handler_t handler,
> + void *priv)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> + struct scp_ipi_desc *ipi_desc;
> +
> + if (!scp) {
> + dev_err(&pdev->dev, "scp device is not ready\n");
> + return -EPROBE_DEFER;
> + }
> +
> + if (WARN_ON(id < 0) || WARN_ON(id >= SCP_IPI_MAX) ||
> + WARN_ON(handler == NULL))
> + return -EINVAL;
> +
> + ipi_desc = scp->ipi_desc;
> + ipi_desc[id].handler = handler;
> + ipi_desc[id].priv = priv;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(scp_ipi_register);
> +
> +void scp_ipi_unregister(struct platform_device *pdev, enum scp_ipi_id id)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> + struct scp_ipi_desc *ipi_desc;
> +
> + if (!scp)
> + return;
> +
> + if (WARN_ON(id < 0) || WARN_ON(id >= SCP_IPI_MAX))
> + return;
> +
> + ipi_desc = scp->ipi_desc;
> + ipi_desc[id].handler = NULL;
> + ipi_desc[id].priv = NULL;
> +}
> +EXPORT_SYMBOL_GPL(scp_ipi_unregister);

I am not seeing any locking taking place in neither scp_ipi_register()
nor scp_ipi_unregister(). Aren't they subject to race conditions,
being exported and all?

> +
> +/*
> + * Copy src to dst, where dst is in SCP SRAM region.
> + * 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 *dst, const void *src, unsigned int len)
> +{
> + void *ptr;
> + u32 val;
> + unsigned int i = 0;
> +
> + if (!IS_ALIGNED((unsigned long)dst, 4)) {
> + ptr = (void *)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);
> + }
> +
> + while (i + 4 <= len) {
> + val = *((u32 *)(src + i));
> + writel_relaxed(val, dst + i);

If dst is not aligned to 4, this is going to write to an address that
is not a multiple of 4, even though it writes a long. Is this ok?
Typically limitations in write size come with alignment limitations.

> + i += 4;
> + }
> + if (i < len) {
> + val = readl_relaxed(dst + i);
> + memcpy(&val, src + i, len - i);
> + writel_relaxed(val, dst + i);
> + }
> +}
> +EXPORT_SYMBOL_GPL(scp_memcpy_aligned);

IIUC this function's symbol does not need to be exported since it is
only used in the current kernel module.

> +
> +int scp_ipi_send(struct platform_device *pdev,
> + enum scp_ipi_id id,
> + void *buf,
> + unsigned int len,
> + unsigned int wait)
> +{
> + struct mtk_scp *scp = platform_get_drvdata(pdev);
> + struct share_obj *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->lock);
> +
> + ret = clk_prepare_enable(scp->clk);
> + if (ret) {
> + dev_err(scp->dev, "failed to enable clock\n");
> + return ret;
> + }
> +
> + /* 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 = -EIO;
> + mutex_unlock(&scp->lock);
> + goto clock_disable;
> + }
> + } while (readl(scp->reg_base + MT8183_HOST_TO_SCP));
> +
> + scp_memcpy_aligned(send_obj->share_buf, buf, len);
> +
> + send_obj->len = len;
> + send_obj->id = id;
> +
> + scp->ipi_id_ack[id] = false;
> + /*
> + * Ensure that all writes to SRAM are committed before sending the
> + * interrupt to SCP.
> + */
> + mb();
> + /* send the command to SCP */
> + writel(MT8183_HOST_IPC_INT_BIT, scp->reg_base + MT8183_HOST_TO_SCP);
> +
> + mutex_unlock(&scp->lock);
> +
> + 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);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(scp_ipi_send);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MediaTek scp IPI interface");
> diff --git a/include/linux/platform_data/mtk_scp.h b/include/linux/platform_data/mtk_scp.h

Considering that the .c files implementing this are in
drivers/remoteproc/, shouldn't this be named
include/linux/remoteproc/mtk_scp.h?


> new file mode 100644
> index 000000000000..b81ac5c7d320
> --- /dev/null
> +++ b/include/linux/platform_data/mtk_scp.h
> @@ -0,0 +1,141 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2018 MediaTek Inc.
> + */
> +
> +#ifndef _MTK_SCP_H
> +#define _MTK_SCP_H
> +
> +#include <linux/platform_device.h>
> +
> +typedef void (*scp_ipi_handler_t) (void *data,
> + unsigned int len,
> + void *priv);
> +
> +/**
> + * enum ipi_id - the id of inter-processor interrupt
> + *
> + * @SCP_IPI_INIT: The interrupt from scp is to notfiy kernel
> + * SCP initialization completed.
> + * IPI_SCP_INIT is sent from SCP when firmware is
> + * loaded. AP doesn't need to send IPI_SCP_INIT
> + * command to SCP.
> + * For other IPI below, AP should send the request
> + * to SCP to trigger the interrupt.
> + * @SCP_IPI_MAX: The maximum IPI number
> + */
> +
> +enum scp_ipi_id {
> + SCP_IPI_INIT = 0,
> + SCP_IPI_VDEC_H264,
> + SCP_IPI_VDEC_VP8,
> + SCP_IPI_VDEC_VP9,
> + SCP_IPI_VENC_H264,
> + SCP_IPI_VENC_VP8,
> + SCP_IPI_MDP_INIT,
> + SCP_IPI_MDP_DEINIT,
> + SCP_IPI_MDP_FRAME,
> + SCP_IPI_DIP,
> + SCP_IPI_ISP_CMD,
> + SCP_IPI_ISP_FRAME,
> + SCP_IPI_FD_CMD,
> + SCP_IPI_CROS_HOST_CMD,
> + SCP_IPI_MAX,
> +};
> +
> +/**
> + * scp_ipi_register - register an ipi function
> + *
> + * @pdev: SCP platform device
> + * @id: IPI ID
> + * @handler: IPI handler
> + * @priv: private data for IPI handler
> + *
> + * Register an ipi function to receive ipi interrupt from SCP.
> + *
> + * Return: Return 0 if ipi registers successfully, otherwise it is failed.
> + */
> +int scp_ipi_register(struct platform_device *pdev,
> + enum scp_ipi_id id,
> + scp_ipi_handler_t handler,
> + void *priv);
> +
> +/**
> + * scp_ipi_unregister - unregister an ipi function
> + *
> + * @pdev: SCP platform device
> + * @id: IPI ID
> + *
> + * Unregister an ipi function to receive ipi interrupt from SCP.
> + */
> +void scp_ipi_unregister(struct platform_device *pdev, enum scp_ipi_id id);
> +
> +/**
> + * scp_ipi_send - send data from AP to scp.
> + *
> + * @pdev: SCP platform device
> + * @id: IPI ID
> + * @buf: the data buffer
> + * @len: the data buffer length
> + * @wait: 1: need ack
> + *
> + * 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.
> + *
> + * Return: Return 0 if sending data successfully, otherwise it is failed.
> + **/
> +int scp_ipi_send(struct platform_device *pdev,
> + enum scp_ipi_id id,
> + void *buf,
> + unsigned int len,
> + unsigned int wait);
> +
> +/**
> + * scp_get_pdev - get SCP's platform device
> + *
> + * @pdev: the platform device of the module requesting SCP platform
> + * device for using SCP API.
> + *
> + * Return: Return NULL if it is failed.
> + * otherwise it is SCP's platform device
> + **/
> +struct platform_device *scp_get_pdev(struct platform_device *pdev);
> +
> +/**
> + * scp_get_vdec_hw_capa - get video decoder hardware capability
> + *
> + * @pdev: SCP platform device
> + *
> + * Return: video decoder hardware capability
> + **/
> +unsigned int scp_get_vdec_hw_capa(struct platform_device *pdev);
> +
> +/**
> + * scp_get_venc_hw_capa - get video encoder hardware capability
> + *
> + * @pdev: SCP platform device
> + *
> + * Return: video encoder hardware capability
> + **/
> +unsigned int scp_get_venc_hw_capa(struct platform_device *pdev);
> +
> +/**
> + * scp_mapping_dm_addr - Mapping SRAM/DRAM to kernel virtual address
> + *
> + * @pdev: SCP platform device
> + * @mem_addr: SCP views memory address
> + *
> + * Mapping the SCP's SRAM address /
> + * DMEM (Data Extended Memory) memory address /
> + * Working buffer memory address to
> + * kernel virtual address.
> + *
> + * Return: Return ERR_PTR(-EINVAL) if mapping failed,
> + * otherwise the mapped kernel virtual address
> + **/
> +void *scp_mapping_dm_addr(struct platform_device *pdev,
> + u32 mem_addr);
> +
> +#endif /* _MTK_SCP_H */
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
>
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

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