Date:   Tue, 1 Dec 2020 15:54:36 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
Cc:     ohad@...ery.com, bjorn.andersson@...aro.org, s-anna@...com,
        linux-remoteproc@...r.kernel.org, robh+dt@...nel.org,
        lee.jones@...aro.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, praneeth@...com,
        rogerq@...com
Subject: Re: [PATCH v2 2/6] remoteproc/pru: Add a PRU remoteproc driver

Hi Grzeg,

I have started to review this set - comments will come over the next few days.

See below for a start. 

On Thu, Nov 19, 2020 at 03:08:46PM +0100, Grzegorz Jaszczyk wrote:
> From: Suman Anna <s-anna@...com>
> 
> The Programmable Real-Time Unit Subsystem (PRUSS) consists of
> dual 32-bit RISC cores (Programmable Real-Time Units, or PRUs)
> for program execution. This patch adds a remoteproc platform
> driver for managing the individual PRU RISC cores life cycle.
> 
> The PRUs do not have a unified address space (have an Instruction
> RAM and a primary Data RAM at both 0x0). The PRU remoteproc driver
> therefore uses a custom remoteproc core ELF loader ops. The added
> .da_to_va ops is only used to provide translations for the PRU
> Data RAMs. This remoteproc driver does not have support for error
> recovery and system suspend/resume features. Different compatibles
> are used to allow providing scalability for instance-specific device
> data if needed. The driver uses a default firmware-name retrieved
> from device-tree for each PRU core, and the firmwares are expected
> to be present in the standard Linux firmware search paths. They can
> also be adjusted by userspace if required through the sysfs interface
> provided by the remoteproc core.
> 
> The PRU remoteproc driver uses a client-driven boot methodology: it
> does _not_ support auto-boot so that the PRU load and boot is dictated
> by the corresponding client drivers for achieving various usecases.
> This allows flexibility for the client drivers or applications to set
> a firmware name (if needed) based on their desired functionality and
> boot the PRU. The sysfs bind and unbind attributes have also been
> suppressed so that the PRU devices cannot be unbound and thereby
> shutdown a PRU from underneath a PRU client driver.
> 
> The driver currently supports the AM335x, AM437x, AM57xx and 66AK2G
> SoCs, and support for other TI SoCs will be added in subsequent
> patches.
> 
> Co-developed-by: Andrew F. Davis <afd@...com>
> Signed-off-by: Andrew F. Davis <afd@...com>
> Signed-off-by: Suman Anna <s-anna@...com>
> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
> ---
> v1->v2:
> - Use PRU_IRAM_ADDR_MASK definition instead of raw 0x3ffff.
> - Convert 'len' argument from int to size_t type in all *da_to_va.
> - Return 0 in case of missing .resource_table for pru_rproc_parse_fw()
>   (move the logic from patch #3 where it was corrected).
> ---
>  drivers/remoteproc/Kconfig     |  12 +
>  drivers/remoteproc/Makefile    |   1 +
>  drivers/remoteproc/pru_rproc.c | 435 +++++++++++++++++++++++++++++++++
>  3 files changed, 448 insertions(+)
>  create mode 100644 drivers/remoteproc/pru_rproc.c
> 
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index d99548fb5dde..3e3865a7cd78 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -125,6 +125,18 @@ config KEYSTONE_REMOTEPROC
>  	  It's safe to say N here if you're not interested in the Keystone
>  	  DSPs or just want to use a bare minimum kernel.
>  
> +config PRU_REMOTEPROC
> +	tristate "TI PRU remoteproc support"
> +	depends on TI_PRUSS
> +	default TI_PRUSS
> +	help
> +	  Support for TI PRU remote processors present within a PRU-ICSS
> +	  subsystem via the remote processor framework.
> +
> +	  Say Y or M here to support the Programmable Realtime Unit (PRU)
> +	  processors on various TI SoCs. It's safe to say N here if you're
> +	  not interested in the PRU or if you are unsure.
> +
>  config QCOM_PIL_INFO
>  	tristate
>  
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index da2ace4ec86c..bb26c9e4ef9c 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_OMAP_REMOTEPROC)		+= omap_remoteproc.o
>  obj-$(CONFIG_WKUP_M3_RPROC)		+= wkup_m3_rproc.o
>  obj-$(CONFIG_DA8XX_REMOTEPROC)		+= da8xx_remoteproc.o
>  obj-$(CONFIG_KEYSTONE_REMOTEPROC)	+= keystone_remoteproc.o
> +obj-$(CONFIG_PRU_REMOTEPROC)		+= pru_rproc.o
>  obj-$(CONFIG_QCOM_PIL_INFO)		+= qcom_pil_info.o
>  obj-$(CONFIG_QCOM_RPROC_COMMON)		+= qcom_common.o
>  obj-$(CONFIG_QCOM_Q6V5_COMMON)		+= qcom_q6v5.o
> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
> new file mode 100644
> index 000000000000..b686f19f9b1a
> --- /dev/null
> +++ b/drivers/remoteproc/pru_rproc.c
> @@ -0,0 +1,435 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PRU-ICSS remoteproc driver for various TI SoCs
> + *
> + * Copyright (C) 2014-2020 Texas Instruments Incorporated - https://www.ti.com/
> + *
> + * Author(s):
> + *	Suman Anna <s-anna@...com>
> + *	Andrew F. Davis <afd@...com>
> + *	Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org> for Texas Instruments
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/pruss_driver.h>
> +#include <linux/remoteproc.h>
> +
> +#include "remoteproc_internal.h"
> +#include "remoteproc_elf_helpers.h"
> +
> +/* PRU_ICSS_PRU_CTRL registers */
> +#define PRU_CTRL_CTRL		0x0000
> +#define PRU_CTRL_STS		0x0004
> +
> +/* CTRL register bit-fields */
> +#define CTRL_CTRL_SOFT_RST_N	BIT(0)
> +#define CTRL_CTRL_EN		BIT(1)
> +#define CTRL_CTRL_SLEEPING	BIT(2)
> +#define CTRL_CTRL_CTR_EN	BIT(3)
> +#define CTRL_CTRL_SINGLE_STEP	BIT(8)
> +#define CTRL_CTRL_RUNSTATE	BIT(15)
> +
> +/* PRU Core IRAM address masks */
> +#define PRU_IRAM_ADDR_MASK	0x3ffff
> +#define PRU0_IRAM_ADDR_MASK	0x34000
> +#define PRU1_IRAM_ADDR_MASK	0x38000
> +
> +/* PRU device addresses for various type of PRU RAMs */
> +#define PRU_IRAM_DA	0	/* Instruction RAM */
> +#define PRU_PDRAM_DA	0	/* Primary Data RAM */
> +#define PRU_SDRAM_DA	0x2000	/* Secondary Data RAM */
> +#define PRU_SHRDRAM_DA	0x10000 /* Shared Data RAM */
> +
> +/**
> + * enum pru_iomem - PRU core memory/register range identifiers
> + *
> + * @PRU_IOMEM_IRAM: PRU Instruction RAM range
> + * @PRU_IOMEM_CTRL: PRU Control register range
> + * @PRU_IOMEM_DEBUG: PRU Debug register range
> + * @PRU_IOMEM_MAX: just keep this one at the end
> + */
> +enum pru_iomem {
> +	PRU_IOMEM_IRAM = 0,
> +	PRU_IOMEM_CTRL,
> +	PRU_IOMEM_DEBUG,
> +	PRU_IOMEM_MAX,
> +};
> +
> +/**
> + * struct pru_rproc - PRU remoteproc structure
> + * @id: id of the PRU core within the PRUSS
> + * @dev: PRU core device pointer
> + * @pruss: back-reference to parent PRUSS structure
> + * @rproc: remoteproc pointer for this PRU core
> + * @mem_regions: data for each of the PRU memory regions
> + * @fw_name: name of firmware image used during loading
> + */
> +struct pru_rproc {
> +	int id;
> +	struct device *dev;
> +	struct pruss *pruss;
> +	struct rproc *rproc;
> +	struct pruss_mem_region mem_regions[PRU_IOMEM_MAX];
> +	const char *fw_name;
> +};
> +
> +static inline u32 pru_control_read_reg(struct pru_rproc *pru, unsigned int reg)
> +{
> +	return readl_relaxed(pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
> +}
> +
> +static inline
> +void pru_control_write_reg(struct pru_rproc *pru, unsigned int reg, u32 val)
> +{
> +	writel_relaxed(val, pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
> +}
> +
> +static int pru_rproc_start(struct rproc *rproc)
> +{
> +	struct device *dev = &rproc->dev;
> +	struct pru_rproc *pru = rproc->priv;
> +	u32 val;
> +
> +	dev_dbg(dev, "starting PRU%d: entry-point = 0x%llx\n",
> +		pru->id, (rproc->bootaddr >> 2));
> +
> +	val = CTRL_CTRL_EN | ((rproc->bootaddr >> 2) << 16);
> +	pru_control_write_reg(pru, PRU_CTRL_CTRL, val);
> +
> +	return 0;
> +}
> +
> +static int pru_rproc_stop(struct rproc *rproc)
> +{
> +	struct device *dev = &rproc->dev;
> +	struct pru_rproc *pru = rproc->priv;
> +	u32 val;
> +
> +	dev_dbg(dev, "stopping PRU%d\n", pru->id);
> +
> +	val = pru_control_read_reg(pru, PRU_CTRL_CTRL);
> +	val &= ~CTRL_CTRL_EN;
> +	pru_control_write_reg(pru, PRU_CTRL_CTRL, val);
> +
> +	return 0;
> +}
> +
> +/*
> + * Convert PRU device address (data spaces only) to kernel virtual address.
> + *
> + * Each PRU has access to all data memories within the PRUSS, accessible at
> + * different ranges. So, look through both its primary and secondary Data
> + * RAMs as well as any shared Data RAM to convert a PRU device address to
> + * kernel virtual address. Data RAM0 is primary Data RAM for PRU0 and Data
> + * RAM1 is primary Data RAM for PRU1.
> + */
> +static void *pru_d_da_to_va(struct pru_rproc *pru, u32 da, size_t len)
> +{
> +	struct pruss_mem_region dram0, dram1, shrd_ram;
> +	struct pruss *pruss = pru->pruss;
> +	u32 offset;
> +	void *va = NULL;
> +
> +	if (len == 0)
> +		return NULL;
> +
> +	dram0 = pruss->mem_regions[PRUSS_MEM_DRAM0];
> +	dram1 = pruss->mem_regions[PRUSS_MEM_DRAM1];
> +	/* PRU1 has its local RAM addresses reversed */
> +	if (pru->id == 1)
> +		swap(dram0, dram1);
> +	shrd_ram = pruss->mem_regions[PRUSS_MEM_SHRD_RAM2];
> +
> +	if (da >= PRU_PDRAM_DA && da + len <= PRU_PDRAM_DA + dram0.size) {
> +		offset = da - PRU_PDRAM_DA;
> +		va = (__force void *)(dram0.va + offset);
> +	} else if (da >= PRU_SDRAM_DA &&
> +		   da + len <= PRU_SDRAM_DA + dram1.size) {
> +		offset = da - PRU_SDRAM_DA;
> +		va = (__force void *)(dram1.va + offset);
> +	} else if (da >= PRU_SHRDRAM_DA &&
> +		   da + len <= PRU_SHRDRAM_DA + shrd_ram.size) {
> +		offset = da - PRU_SHRDRAM_DA;
> +		va = (__force void *)(shrd_ram.va + offset);
> +	}
> +
> +	return va;
> +}
> +
> +/*
> + * Convert PRU device address (instruction space) to kernel virtual address.
> + *
> + * A PRU does not have an unified address space. Each PRU has its very own
> + * private Instruction RAM, and its device address is identical to that of
> + * its primary Data RAM device address.
> + */
> +static void *pru_i_da_to_va(struct pru_rproc *pru, u32 da, size_t len)
> +{
> +	u32 offset;
> +	void *va = NULL;
> +
> +	if (len == 0)
> +		return NULL;
> +
> +	if (da >= PRU_IRAM_DA &&
> +	    da + len <= PRU_IRAM_DA + pru->mem_regions[PRU_IOMEM_IRAM].size) {
> +		offset = da - PRU_IRAM_DA;
> +		va = (__force void *)(pru->mem_regions[PRU_IOMEM_IRAM].va +
> +				      offset);
> +	}
> +
> +	return va;
> +}
> +
> +/*
> + * Provide address translations for only PRU Data RAMs through the remoteproc
> + * core for any PRU client drivers. The PRU Instruction RAM access is restricted
> + * only to the PRU loader code.
> + */
> +static void *pru_rproc_da_to_va(struct rproc *rproc, u64 da, size_t len)
> +{
> +	struct pru_rproc *pru = rproc->priv;
> +
> +	return pru_d_da_to_va(pru, da, len);
> +}
> +
> +/* PRU-specific address translator used by PRU loader. */
> +static void *pru_da_to_va(struct rproc *rproc, u64 da, size_t len, bool is_iram)
> +{
> +	struct pru_rproc *pru = rproc->priv;
> +	void *va;
> +
> +	if (is_iram)
> +		va = pru_i_da_to_va(pru, da, len);
> +	else
> +		va = pru_d_da_to_va(pru, da, len);
> +
> +	return va;
> +}
> +
> +static struct rproc_ops pru_rproc_ops = {
> +	.start		= pru_rproc_start,
> +	.stop		= pru_rproc_stop,
> +	.da_to_va	= pru_rproc_da_to_va,
> +};
> +
> +static int
> +pru_rproc_load_elf_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;
> +		bool is_iram;
> +		void *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 */
> +		is_iram = phdr->p_flags & PF_X;
> +		ptr = pru_da_to_va(rproc, da, memsz, is_iram);
> +		if (!ptr) {
> +			dev_err(dev, "bad phdr da 0x%x mem 0x%x\n", da, memsz);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		/* skip the memzero logic performed by remoteproc ELF loader */
> +		if (!phdr->p_filesz)
> +			continue;

I don't see the need to do all this if phdr->p_filesz is not valid.  I would move
this below the check for PT_LOAD above.  Otherwise people are looking for some
kind of hidden logic when there isn't any.  The comment should probably go
after the memcpy().

I am running out of time for today and will continue tomorrow.

> +
> +		memcpy(ptr, elf_data + phdr->p_offset, filesz);
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * Use a custom parse_fw callback function for dealing with PRU firmware
> + * specific sections.
> + */
> +static int pru_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> +	int ret;
> +
> +	/* load optional rsc table */
> +	ret = rproc_elf_load_rsc_table(rproc, fw);
> +	if (ret == -EINVAL)
> +		dev_dbg(&rproc->dev, "no resource table found for this fw\n");
> +	else if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +/*
> + * Compute PRU id based on the IRAM addresses. The PRU IRAMs are
> + * always at a particular offset within the PRUSS address space.
> + */
> +static int pru_rproc_set_id(struct pru_rproc *pru)
> +{
> +	int ret = 0;
> +
> +	switch (pru->mem_regions[PRU_IOMEM_IRAM].pa & PRU_IRAM_ADDR_MASK) {
> +	case PRU0_IRAM_ADDR_MASK:
> +		pru->id = 0;
> +		break;
> +	case PRU1_IRAM_ADDR_MASK:
> +		pru->id = 1;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int pru_rproc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct platform_device *ppdev = to_platform_device(dev->parent);
> +	struct pru_rproc *pru;
> +	const char *fw_name;
> +	struct rproc *rproc = NULL;
> +	struct resource *res;
> +	int i, ret;
> +	const char *mem_names[PRU_IOMEM_MAX] = { "iram", "control", "debug" };
> +
> +	ret = of_property_read_string(np, "firmware-name", &fw_name);
> +	if (ret) {
> +		dev_err(dev, "unable to retrieve firmware-name %d\n", ret);
> +		return ret;
> +	}
> +
> +	rproc = devm_rproc_alloc(dev, pdev->name, &pru_rproc_ops, fw_name,
> +				 sizeof(*pru));
> +	if (!rproc) {
> +		dev_err(dev, "rproc_alloc failed\n");
> +		return -ENOMEM;
> +	}
> +	/* use a custom load function to deal with PRU-specific quirks */
> +	rproc->ops->load = pru_rproc_load_elf_segments;
> +
> +	/* use a custom parse function to deal with PRU-specific resources */
> +	rproc->ops->parse_fw = pru_rproc_parse_fw;
> +
> +	/* error recovery is not supported for PRUs */
> +	rproc->recovery_disabled = true;
> +
> +	/*
> +	 * rproc_add will auto-boot the processor normally, but this is not
> +	 * desired with PRU client driven boot-flow methodology. A PRU
> +	 * application/client driver will boot the corresponding PRU
> +	 * remote-processor as part of its state machine either through the
> +	 * remoteproc sysfs interface or through the equivalent kernel API.
> +	 */
> +	rproc->auto_boot = false;
> +
> +	pru = rproc->priv;
> +	pru->dev = dev;
> +	pru->pruss = platform_get_drvdata(ppdev);
> +	pru->rproc = rproc;
> +	pru->fw_name = fw_name;
> +
> +	for (i = 0; i < ARRAY_SIZE(mem_names); i++) {
> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   mem_names[i]);
> +		pru->mem_regions[i].va = devm_ioremap_resource(dev, res);
> +		if (IS_ERR(pru->mem_regions[i].va)) {
> +			dev_err(dev, "failed to parse and map memory resource %d %s\n",
> +				i, mem_names[i]);
> +			ret = PTR_ERR(pru->mem_regions[i].va);
> +			return ret;
> +		}
> +		pru->mem_regions[i].pa = res->start;
> +		pru->mem_regions[i].size = resource_size(res);
> +
> +		dev_dbg(dev, "memory %8s: pa %pa size 0x%zx va %pK\n",
> +			mem_names[i], &pru->mem_regions[i].pa,
> +			pru->mem_regions[i].size, pru->mem_regions[i].va);
> +	}
> +
> +	ret = pru_rproc_set_id(pru);
> +	if (ret < 0)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, rproc);
> +
> +	ret = devm_rproc_add(dev, pru->rproc);
> +	if (ret) {
> +		dev_err(dev, "rproc_add failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	dev_dbg(dev, "PRU rproc node %pOF probed successfully\n", np);
> +
> +	return 0;
> +}
> +
> +static int pru_rproc_remove(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct rproc *rproc = platform_get_drvdata(pdev);
> +
> +	dev_dbg(dev, "%s: removing rproc %s\n", __func__, rproc->name);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id pru_rproc_match[] = {
> +	{ .compatible = "ti,am3356-pru", },
> +	{ .compatible = "ti,am4376-pru", },
> +	{ .compatible = "ti,am5728-pru", },
> +	{ .compatible = "ti,k2g-pru",    },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, pru_rproc_match);
> +
> +static struct platform_driver pru_rproc_driver = {
> +	.driver = {
> +		.name   = "pru-rproc",
> +		.of_match_table = pru_rproc_match,
> +		.suppress_bind_attrs = true,
> +	},
> +	.probe  = pru_rproc_probe,
> +	.remove = pru_rproc_remove,
> +};
> +module_platform_driver(pru_rproc_driver);
> +
> +MODULE_AUTHOR("Suman Anna <s-anna@...com>");
> +MODULE_AUTHOR("Andrew F. Davis <afd@...com>");
> +MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>");
> +MODULE_DESCRIPTION("PRU-ICSS Remote Processor Driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.29.0
> 

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