Re: [PATCH 1/5] misc: Add Synopsys DesignWare xData IP driver

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Oct 29, 2020 at 08:13:36PM +0100, Gustavo Pimentel wrote:
> Add Synopsys DesignWare xData IP driver. This driver enables/disables
> the PCI traffic generator module pertain to the Synopsys DesignWare
> prototype.
> 
> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> ---
>  drivers/misc/dw-xdata-pcie.c | 395 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 395 insertions(+)
>  create mode 100644 drivers/misc/dw-xdata-pcie.c
> 
> diff --git a/drivers/misc/dw-xdata-pcie.c b/drivers/misc/dw-xdata-pcie.c
> new file mode 100644
> index 00000000..b529dae
> --- /dev/null
> +++ b/drivers/misc/dw-xdata-pcie.c
> @@ -0,0 +1,395 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020 Synopsys, Inc. and/or its affiliates.
> + * Synopsys DesignWare xData driver
> + *
> + * Author: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> + */
> +
> +#include <linux/pci-epf.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/pci.h>
> +
> +#define DW_XDATA_EP_MEM_OFFSET		0x8000000
> +
> +static DEFINE_MUTEX(xdata_lock);
> +
> +struct dw_xdata_pcie_data {
> +	/* xData registers location */
> +	enum pci_barno			rg_bar;
> +	off_t				rg_off;
> +	size_t				rg_sz;
> +};
> +
> +static const struct dw_xdata_pcie_data snps_edda_data = {
> +	/* xData registers location */
> +	.rg_bar				= BAR_0,
> +	.rg_off				= 0x00000000,   /*   0 Kbytes */
> +	.rg_sz				= 0x0000012c,   /* 300  bytes */
> +};
> +
> +static int dw_xdata_command_set(const char *val, const struct kernel_param *kp);
> +static const struct kernel_param_ops xdata_command_ops = {
> +	.set = dw_xdata_command_set,
> +};
> +
> +static char command;
> +module_param_cb(command, &xdata_command_ops, &command, 0644);
> +MODULE_PARM_DESC(command, "xData command");

Please do not add new module parameters.  This is not the 1990's, we
have better ways of getting data into a driver.

> +
> +static struct pci_dev *priv;

You are only going to support one PCI device in the system at once?
That's not needed, again, this isn't the 1990's, please use
device-specific data and you will be fine, no "global" variables needed.

> +
> +union dw_xdata_control_reg {
> +	u32 reg;
> +	struct {
> +		u32 doorbell    : 1;			/* 00 */
> +		u32 is_write    : 1;			/* 01 */
> +		u32 length      : 12;			/* 02..13 */
> +		u32 is_64       : 1;			/* 14 */
> +		u32 ep		: 1;			/* 15 */
> +		u32 pattern_inc : 1;			/* 16 */
> +		u32 ie		: 1;			/* 17 */
> +		u32 no_addr_inc : 1;			/* 18 */
> +		u32 trigger     : 1;			/* 19 */
> +		u32 _reserved0  : 12;			/* 20..31 */
> +	};
> +} __packed;

What is the endian-ness of these structures?  That needs to be defined
somewhere, right?

> +
> +union dw_xdata_status_reg {
> +	u32 reg;
> +	struct {
> +		u32 done	: 1;			/* 00 */
> +		u32 _reserved0  : 15;			/* 01..15 */
> +		u32 version     : 16;			/* 16..31 */
> +	};
> +} __packed;
> +
> +union dw_xdata_xperf_control_reg {
> +	u32 reg;
> +	struct {
> +		u32 _reserved0  : 4;			/* 00..03 */
> +		u32 reset       : 1;			/* 04 */
> +		u32 enable      : 1;			/* 05 */
> +		u32 _reserved1  : 26;			/* 06..31 */
> +	};
> +} __packed;
> +
> +union _addr {
> +	u64 reg;
> +	struct {
> +		u32 lsb;
> +		u32 msb;
> +	};
> +};
> +
> +struct dw_xdata_regs {
> +	union _addr addr;				/* 0x000..0x004 */
> +	u32 burst_cnt;					/* 0x008 */
> +	u32 control;					/* 0x00c */
> +	u32 pattern;					/* 0x010 */
> +	u32 status;					/* 0x014 */
> +	u32 RAM_addr;					/* 0x018 */
> +	u32 RAM_port;					/* 0x01c */
> +	u32 _reserved0[14];				/* 0x020..0x054 */
> +	u32 perf_control;				/* 0x058 */
> +	u32 _reserved1[41];				/* 0x05c..0x0fc */
> +	union _addr wr_cnt;				/* 0x100..0x104 */
> +	union _addr rd_cnt;				/* 0x108..0x10c */
> +} __packed;

Why packed?  Does this cross the user/kernel boundry?  If so, please use
the correct data types for the (__u32 not u32).


> +
> +struct dw_xdata_region {
> +	phys_addr_t paddr;				/* physical address */
> +	void __iomem *vaddr;				/* virtual address */
> +	size_t sz;					/* size */
> +};
> +
> +struct dw_xdata {
> +	struct dw_xdata_region rg_region;		/* registers */
> +	size_t max_wr_len;				/* max xfer len */
> +	size_t max_rd_len;				/* max xfer len */
> +};
> +
> +static inline struct dw_xdata_regs __iomem *__dw_regs(struct dw_xdata *dw)
> +{
> +	return dw->rg_region.vaddr;
> +}
> +
> +#define SET(dw, name, value) \
> +	writel(value, &(__dw_regs(dw)->name))
> +
> +#define GET(dw, name) \
> +	readl(&(__dw_regs(dw)->name))

Just write out readl() and writel() in the driver, it makes more sense
to anyone trying to read the code.

> +
> +#ifdef CONFIG_64BIT
> +#define SET_64(dw, name, value) \
> +	writel(value, &(__dw_regs(dw)->name))
> +
> +#define GET_64(dw, name) \
> +	readq(&(__dw_regs(dw)->name))
> +#endif /* CONFIG_64BIT */

No need for this #ifdef, right?


> +
> +static void dw_xdata_stop(struct pci_dev *pdev)
> +{
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +	u32 tmp = GET(dw, burst_cnt);
> +
> +	if (tmp & 0x80000000) {
> +		tmp &= 0x7fffffff;
> +		SET(dw, burst_cnt, tmp);
> +	}
> +}
> +
> +static void dw_xdata_start(struct pci_dev *pdev, bool write)
> +{
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +	union dw_xdata_control_reg control;
> +	union dw_xdata_status_reg status;
> +
> +	/* Stop first if xfer in progress */
> +	dw_xdata_stop(pdev);
> +
> +	/* Clear status register */
> +	SET(dw, status, 0x0);
> +
> +	/* Burst count register set for continuous until stopped */
> +	SET(dw, burst_cnt, 0x80001001);
> +
> +	/* Pattern register */
> +	SET(dw, pattern, 0x0);
> +
> +	/* Control register */
> +	control.reg = 0x0;
> +	control.doorbell = true;
> +	control.is_write = write;
> +	if (write)
> +		control.length = dw->max_wr_len;
> +	else
> +		control.length = dw->max_rd_len;
> +	control.pattern_inc = true;
> +	control.no_addr_inc = true;
> +	SET(dw, control, control.reg);
> +
> +	usleep_range(100, 150);
> +
> +	status.reg = GET(dw, status);
> +	if (!status.done)
> +		pci_info(pdev, "xData: started %s direction\n",
> +			 write ? "write" : "read");

Don't be noisy if all is well.  You have a lot of "debugging" messages
in this driver, please drop them all down to the debug level, or just
remove them.


> +}
> +
> +static u64 dw_xdata_perf_meas(struct pci_dev *pdev, u64 *wr, u64 *rd)
> +{
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +
> +	#ifdef CONFIG_64BIT
> +		*wr = GET_64(dw, wr_cnt.reg);
> +
> +		*rd = GET_64(dw, rd_cnt.reg);
> +	#else /* CONFIG_64BIT */
> +		*wr = GET(dw, wr_cnt.msb);
> +		*wr <<= 32;
> +		*wr |= GET(dw, wr_cnt.lsb);
> +
> +		*rd = GET(dw, rd_cnt.msb);
> +		*rd <<= 32;
> +		*rd |= GET(dw, rd_cnt.lsb);
> +	#endif /* CONFIG_64BIT */
> +
> +	return jiffies;

Why are you returning jiffies???


> +}
> +
> +static u64 dw_xdata_perf_diff(u64 *m1, u64 *m2, u64 time)
> +{
> +	u64 rate;
> +
> +	rate = (*m1 - *m2);
> +	rate *= (1000 * 1000 * 1000);
> +	rate >>= 20;
> +	rate = DIV_ROUND_CLOSEST_ULL(rate, time);
> +
> +	return rate;
> +}
> +
> +static void dw_xdata_perf(struct pci_dev *pdev)
> +{
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +	union dw_xdata_xperf_control_reg control;
> +	u64 wr[2], rd[2], time[2], rate[2], diff;
> +
> +	/* First measurement */
> +	control.reg = 0x0;
> +	control.enable = false;
> +	SET(dw, perf_control, control.reg);
> +	time[0] = dw_xdata_perf_meas(pdev, &wr[0], &rd[0]);
> +	control.enable = true;
> +	SET(dw, perf_control, control.reg);
> +
> +	/* Delay 100ms */
> +	mdelay(100);
> +
> +	/* Second measurement */
> +	control.reg = 0x0;
> +	control.enable = false;
> +	SET(dw, perf_control, control.reg);
> +	time[1] = dw_xdata_perf_meas(pdev, &wr[1], &rd[1]);
> +	control.enable = true;
> +	SET(dw, perf_control, control.reg);
> +
> +	/* Calculations */
> +	diff = jiffies_to_nsecs(time[1] - time[0]);
> +
> +	/* Write performance */
> +	rate[0] = dw_xdata_perf_diff(&wr[1], &wr[0], diff);
> +
> +	/* Read performance */
> +	rate[1] = dw_xdata_perf_diff(&rd[1], &rd[0], diff);
> +
> +	pci_info(pdev,
> +		 "xData: time=%llu us, write=%llu MB/s, read=%llu MB/s\n",
> +		 diff, rate[0], rate[1]);

Again, be quiet.

> +}
> +
> +static int dw_xdata_command_set(const char *val, const struct kernel_param *kp)
> +{
> +	int ret = -EBUSY;
> +
> +	mutex_lock(&xdata_lock);
> +	if (!priv)
> +		goto err;
> +
> +	ret = param_set_charp(val, kp);
> +	if (ret)
> +		goto err;
> +
> +	switch (*val) {
> +	case 'w':
> +	case 'W':
> +		pci_info(priv, "xData: requested write transfer\n");
> +		dw_xdata_start(priv, true);
> +		break;
> +	case 'r':
> +	case 'R':
> +		pci_info(priv, "xData: requested read transfer\n");
> +		dw_xdata_start(priv, false);
> +		break;
> +	case 'p':
> +	case 'P':
> +		pci_info(priv, "xData: requested performance analysis\n");
> +		dw_xdata_perf(priv);
> +		break;
> +	default:
> +		pci_info(priv, "xData: requested stop any transfer\n");
> +		dw_xdata_stop(priv);
> +		break;
> +	}
> +
> +err:
> +	mutex_unlock(&xdata_lock);
> +
> +	return ret;
> +}
> +
> +static int dw_xdata_pcie_probe(struct pci_dev *pdev,
> +			       const struct pci_device_id *pid)
> +{
> +	const struct dw_xdata_pcie_data *pdata = (void *)pid->driver_data;
> +	struct device *dev = &pdev->dev;
> +	struct dw_xdata *dw;
> +	u64 addr;
> +	int err;
> +
> +	priv = NULL;
> +
> +	/* Enable PCI device */
> +	err = pcim_enable_device(pdev);
> +	if (err) {
> +		pci_err(pdev, "enabling device failed\n");
> +		return err;
> +	}
> +
> +	/* Mapping PCI BAR regions */
> +	err = pcim_iomap_regions(pdev, BIT(pdata->rg_bar), pci_name(pdev));
> +	if (err) {
> +		pci_err(pdev, "xData BAR I/O remapping failed\n");
> +		return err;
> +	}
> +
> +	pci_set_master(pdev);
> +
> +	/* Allocate memory */
> +	dw = devm_kzalloc(dev, sizeof(*dw), GFP_KERNEL);
> +	if (!dw)
> +		return -ENOMEM;
> +
> +	/* Data structure initialization */
> +	dw->rg_region.vaddr = pcim_iomap_table(pdev)[pdata->rg_bar];
> +	if (!dw->rg_region.vaddr)
> +		return -ENOMEM;
> +
> +	dw->rg_region.vaddr += pdata->rg_off;
> +	dw->rg_region.paddr = pdev->resource[pdata->rg_bar].start;
> +	dw->rg_region.paddr += pdata->rg_off;
> +	dw->rg_region.sz = pdata->rg_sz;
> +
> +	dw->max_wr_len = pcie_get_mps(pdev);
> +	dw->max_wr_len >>= 2;
> +
> +	dw->max_rd_len = pcie_get_readrq(pdev);
> +	dw->max_rd_len >>= 2;
> +
> +	SET(dw, RAM_addr, 0x0);
> +	SET(dw, RAM_port, 0x0);
> +
> +	addr = dw->rg_region.paddr + DW_XDATA_EP_MEM_OFFSET;
> +#ifdef CONFIG_64BIT
> +	SET_64(dw, addr.reg, addr);
> +#else /* CONFIG_64BIT */
> +	SET(dw, addr.lsb, lower_32_bits(addr));
> +	SET(dw, addr.msb, upper_32_bits(addr));
> +#endif /* CONFIG_64BIT */
> +	pci_info(pdev, "xData: target address = 0x%.16llx\n", addr);
> +
> +	pci_info(pdev, "xData: wr_len=%zu, rd_len=%zu\n",
> +		 dw->max_wr_len * 4, dw->max_rd_len * 4);

Drivers need to be quiet...

thanks,

greg k-h