Re: [PATCH v2 11/14] misc: rp1: RaspberryPi RP1 misc driver

[Herve Codina <herve.codina@bootlin.com>]

Hi Andrea,

Nice to see that other PCI drivers will use the DT overlay over PCI feature!

On Mon,  7 Oct 2024 14:39:54 +0200
Andrea della Porta <andrea.porta@suse.com> wrote:

> The RaspberryPi RP1 is a PCI multi function device containing
> peripherals ranging from Ethernet to USB controller, I2C, SPI
> and others.
> 
> Implement a bare minimum driver to operate the RP1, leveraging
> actual OF based driver implementations for the on-board peripherals
> by loading a devicetree overlay during driver probe.
> 
> The peripherals are accessed by mapping MMIO registers starting
> from PCI BAR1 region.
> 
> With the overlay approach we can achieve more generic and agnostic
> approach to managing this chipset, being that it is a PCI endpoint
> and could possibly be reused in other hw implementations. The
> presented approach is also used by Bootlin's Microchip LAN966x
> patchset (see link) as well, for a similar chipset.
> 
> Since the gpio line names should be provided by the user, there
> is an interface through configfs that allows the userspace to
> load a DT overlay that will provide gpio-line-names property.
> The interface can be invoked like this:
> 
> cat rpi-rp1-gpios-5-b.dtbo > /sys/kernel/config/rp1-cfg/gpio_set_names
> 
> and is designed to be similar to what users are already used to
> from distro with downstream kernel.
> 
> For reasons why this driver is contained in drivers/misc, please
> check the links.
> 
> This driver is heavily based on downstream code from RaspberryPi
> Foundation, and the original author is Phil Elwell.
> 
> Link: https://datasheets.raspberrypi.com/rp1/rp1-peripherals.pdf
> Link: https://lore.kernel.org/all/20240612140208.GC1504919@google.com/
> Link: https://lore.kernel.org/all/83f7fa09-d0e6-4f36-a27d-cee08979be2a@app.fastmail.com/
> Link: https://lore.kernel.org/all/2024081356-mutable-everyday-6f9d@gregkh/
> Link: https://lore.kernel.org/all/20240808154658.247873-1-herve.codina@bootlin.com/
> 
> Signed-off-by: Andrea della Porta <andrea.porta@suse.com>

...
> --- /dev/null
> +++ b/drivers/misc/rp1/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_MISC_RP1)		+= rp1-pci.o
> +rp1-pci-objs			:= rp1_pci.o rp1-pci.dtbo.o
> +
> +DTC_FLAGS_rp1-pci += -@
Why do you need to add the symbol table (-@ option) in your dtbo ?

...
> diff --git a/drivers/misc/rp1/rp1_pci.c b/drivers/misc/rp1/rp1_pci.c
> new file mode 100644
> index 000000000000..a1f7bf1804c0
> --- /dev/null
> +++ b/drivers/misc/rp1/rp1_pci.c
> @@ -0,0 +1,365 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018-24 Raspberry Pi Ltd.
> + * All rights reserved.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clkdev.h>
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_platform.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +
> +#include "rp1_pci.h"
> +
> +#define RP1_DRIVER_NAME		"rp1"
> +
> +#define RP1_HW_IRQ_MASK		GENMASK(5, 0)
> +
> +#define REG_SET			0x800
> +#define REG_CLR			0xc00
> +
> +/* MSI-X CFG registers start at 0x8 */
> +#define MSIX_CFG(x) (0x8 + (4 * (x)))
> +
> +#define MSIX_CFG_IACK_EN        BIT(3)
> +#define MSIX_CFG_IACK           BIT(2)
> +#define MSIX_CFG_ENABLE         BIT(0)
> +
> +/* Address map */
> +#define RP1_PCIE_APBS_BASE	0x108000
> +
> +/* Interrupts */
> +#define RP1_INT_IO_BANK0	0
> +#define RP1_INT_IO_BANK1	1
> +#define RP1_INT_IO_BANK2	2
> +#define RP1_INT_AUDIO_IN	3
> +#define RP1_INT_AUDIO_OUT	4
> +#define RP1_INT_PWM0		5
> +#define RP1_INT_ETH		6
> +#define RP1_INT_I2C0		7
> +#define RP1_INT_I2C1		8
> +#define RP1_INT_I2C2		9
> +#define RP1_INT_I2C3		10
> +#define RP1_INT_I2C4		11
> +#define RP1_INT_I2C5		12
> +#define RP1_INT_I2C6		13
> +#define RP1_INT_I2S0		14
> +#define RP1_INT_I2S1		15
> +#define RP1_INT_I2S2		16
> +#define RP1_INT_SDIO0		17
> +#define RP1_INT_SDIO1		18
> +#define RP1_INT_SPI0		19
> +#define RP1_INT_SPI1		20
> +#define RP1_INT_SPI2		21
> +#define RP1_INT_SPI3		22
> +#define RP1_INT_SPI4		23
> +#define RP1_INT_SPI5		24
> +#define RP1_INT_UART0		25
> +#define RP1_INT_TIMER_0		26
> +#define RP1_INT_TIMER_1		27
> +#define RP1_INT_TIMER_2		28
> +#define RP1_INT_TIMER_3		29
> +#define RP1_INT_USBHOST0	30
> +#define RP1_INT_USBHOST0_0	31
> +#define RP1_INT_USBHOST0_1	32
> +#define RP1_INT_USBHOST0_2	33
> +#define RP1_INT_USBHOST0_3	34
> +#define RP1_INT_USBHOST1	35
> +#define RP1_INT_USBHOST1_0	36
> +#define RP1_INT_USBHOST1_1	37
> +#define RP1_INT_USBHOST1_2	38
> +#define RP1_INT_USBHOST1_3	39
> +#define RP1_INT_DMA		40
> +#define RP1_INT_PWM1		41
> +#define RP1_INT_UART1		42
> +#define RP1_INT_UART2		43
> +#define RP1_INT_UART3		44
> +#define RP1_INT_UART4		45
> +#define RP1_INT_UART5		46
> +#define RP1_INT_MIPI0		47
> +#define RP1_INT_MIPI1		48
> +#define RP1_INT_VIDEO_OUT	49
> +#define RP1_INT_PIO_0		50
> +#define RP1_INT_PIO_1		51
> +#define RP1_INT_ADC_FIFO	52
> +#define RP1_INT_PCIE_OUT	53
> +#define RP1_INT_SPI6		54
> +#define RP1_INT_SPI7		55
> +#define RP1_INT_SPI8		56
> +#define RP1_INT_SYSCFG		58
> +#define RP1_INT_CLOCKS_DEFAULT	59
> +#define RP1_INT_VBUSCTRL	60
> +#define RP1_INT_PROC_MISC	57
> +#define RP1_INT_END		61
> +
> +struct rp1_dev {
> +	struct pci_dev *pdev;
> +	struct device *dev;
> +	struct clk *sys_clk;
> +	struct irq_domain *domain;
> +	struct irq_data *pcie_irqds[64];
> +	void __iomem *bar1;
> +	int ovcs_id;
> +	bool level_triggered_irq[RP1_INT_END];
> +};
> +
> +static void dump_bar(struct pci_dev *pdev, unsigned int bar)
> +{
> +	dev_info(&pdev->dev,
> +		 "bar%d %pR\n",
> +		 bar,
> +		 pci_resource_n(pdev, bar));
> +}

Is this dump_bar() really needed ?

...
> +static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *rp1_node;
> +	struct reset_control *reset;
> +	struct rp1_dev *rp1;
> +	int err  = 0;
> +	int i;
> +
> +	rp1_node = dev_of_node(dev);
> +	if (!rp1_node) {
> +		dev_err(dev, "Missing of_node for device\n");
> +		return -EINVAL;
> +	}
> +
> +	rp1 = devm_kzalloc(&pdev->dev, sizeof(*rp1), GFP_KERNEL);
> +	if (!rp1)
> +		return -ENOMEM;
> +
> +	rp1->pdev = pdev;
> +	rp1->dev = &pdev->dev;
> +
> +	reset = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> +	if (IS_ERR(reset))
> +		return PTR_ERR(reset);
> +	reset_control_reset(reset);

This device is a PCI device.
Seems strange to get the reset control line for a PCI device.

> +
> +	dump_bar(pdev, 0);
> +	dump_bar(pdev, 1);
No sure those 2 dump_bar() calls are really needed.
> +
> +	if (pci_resource_len(pdev, 1) <= 0x10000) {
> +		dev_err(&pdev->dev,
> +			"Not initialised - is the firmware running?\n");
> +		return -EINVAL;
> +	}
> +
> +	err = pcim_enable_device(pdev);
> +	if (err < 0) {
> +		dev_err(&pdev->dev, "Enabling PCI device has failed: %d",
> +			err);
> +		return err;
> +	}
> +
> +	rp1->bar1 = pcim_iomap(pdev, 1, 0);
> +	if (!rp1->bar1) {
> +		dev_err(&pdev->dev, "Cannot map PCI BAR\n");
> +		return -EIO;
> +	}
> +
> +	u32 dtbo_size = __dtbo_rp1_pci_end - __dtbo_rp1_pci_begin;
> +	void *dtbo_start = __dtbo_rp1_pci_begin;

Those declarations should be move at the beginning of the function.

> +
> +	err = of_overlay_fdt_apply(dtbo_start, dtbo_size, &rp1->ovcs_id, rp1_node);
> +	if (err)
> +		return err;
> +

Maybe applying the overlay should be done after the interrupt controller
is ready.

> +	pci_set_master(pdev);
> +
> +	err = pci_alloc_irq_vectors(pdev, RP1_INT_END, RP1_INT_END,
> +				    PCI_IRQ_MSIX);
> +	if (err != RP1_INT_END) {
> +		dev_err(&pdev->dev, "pci_alloc_irq_vectors failed - %d\n", err);
> +		goto err_unload_overlay;
> +	}
> +
> +	pci_set_drvdata(pdev, rp1);
> +	rp1->domain = irq_domain_add_linear(of_find_node_by_name(NULL, "pci-ep-bus"), RP1_INT_END,
> +					    &rp1_domain_ops, rp1);
> +
> +	for (i = 0; i < RP1_INT_END; i++) {
> +		int irq = irq_create_mapping(rp1->domain, i);
> +
> +		if (irq < 0) {
> +			dev_err(&pdev->dev, "failed to create irq mapping\n");
> +			err = irq;
> +			goto err_unload_overlay;
> +		}
> +		irq_set_chip_and_handler(irq, &rp1_irq_chip, handle_level_irq);
> +		irq_set_probe(irq);
> +		irq_set_chained_handler_and_data(pci_irq_vector(pdev, i),
> +						 rp1_chained_handle_irq, rp1);
> +	}
> +
> +	err = of_platform_default_populate(rp1_node, NULL, dev);
> +	if (err)
> +		goto err_unload_overlay;
> +
> +	return 0;
> +
> +err_unload_overlay:
> +	of_overlay_remove(&rp1->ovcs_id);
> +
> +	return err;
> +}
> +
> +static void rp1_remove(struct pci_dev *pdev)
> +{
> +	struct rp1_dev *rp1 = pci_get_drvdata(pdev);
> +	struct device *dev = &pdev->dev;
> +
> +	of_platform_depopulate(dev);
> +	of_overlay_remove(&rp1->ovcs_id);
> +
> +	clk_unregister(rp1->sys_clk);

Unless I missed something, rp1->sys_clk is never set in probe().
If this is correct, clk_unregister() should be removed and also
the related clk header files.

The interrupt controller created at probe() should be destroyed at remove().

> +}
> +

...
> diff --git a/drivers/misc/rp1/rp1_pci.h b/drivers/misc/rp1/rp1_pci.h
> new file mode 100644
> index 000000000000..7982f13bad9b
> --- /dev/null
> +++ b/drivers/misc/rp1/rp1_pci.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +/*
> + * Copyright (c) 2018-24 Raspberry Pi Ltd.
> + * All rights reserved.
> + */
> +
> +#ifndef _RP1_EXTERN_H_
> +#define _RP1_EXTERN_H_
> +
> +extern char __dtbo_rp1_pci_begin[];
> +extern char __dtbo_rp1_pci_end[];
> +
> +#endif

These two symbols are only used by the rp1_pci.c file.
Not sure that the rp1_pci.h is needed.
Simply declare the symbols in the rp1_pci.c file.


Best regards,
Hervé