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Message-ID: <ZGy3b7ZfNwWoGDTu@surfacebook>
Date: Tue, 23 May 2023 15:54:07 +0300
From: andy.shevchenko@...il.com
To: Yinbo Zhu <zhuyinbo@...ngson.cn>
Cc: Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, Jianmin Lv <lvjianmin@...ngson.cn>,
wanghongliang@...ngson.cn, Liu Peibao <liupeibao@...ngson.cn>,
loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH v11 2/2] spi: loongson: add bus driver for the loongson
spi controller
Mon, May 22, 2023 at 03:10:30PM +0800, Yinbo Zhu kirjoitti:
> This bus driver supports the Loongson SPI hardware controller in the
> Loongson platforms and supports to use DTS and PCI framework to
> register SPI device resources.
It's polite to add reviewers of the previous versions to the Cc list.
...
> +static void loongson_spi_set_clk(struct loongson_spi *loongson_spi, unsigned int hz)
> +{
> + unsigned char val;
> + unsigned int div, div_tmp;
> + const char rdiv[12] = {0, 1, 4, 2, 3, 5, 6, 7, 8, 9, 10, 11};
static?
> +
> + div = clamp_val(DIV_ROUND_UP_ULL(loongson_spi->clk_rate, hz), 2, 4096);
> + div_tmp = rdiv[fls(div - 1)];
> + loongson_spi->spcr = (div_tmp & GENMASK(1, 0)) >> 0;
> + loongson_spi->sper = (div_tmp & GENMASK(3, 2)) >> 2;
> + val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
> + loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPCR_REG, (val & ~3) |
> + loongson_spi->spcr);
> + val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPER_REG);
> + loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPER_REG, (val & ~3) |
> + loongson_spi->sper);
> + loongson_spi->hz = hz;
> +}
...
> +static int loongson_spi_update_state(struct loongson_spi *loongson_spi,
> + struct spi_device *spi, struct spi_transfer *t)
> +{
> + unsigned int hz;
> +
> + if (t)
> + hz = t->speed_hz;
And if t is NULL? hz will be uninitialized. Don't you get a compiler warning?
(Always test your code with `make W=1 ...`)
> + if (hz && loongson_spi->hz != hz)
> + loongson_spi_set_clk(loongson_spi, hz);
> +
> + if ((spi->mode ^ loongson_spi->mode) & SPI_MODE_X_MASK)
> + loongson_spi_set_mode(loongson_spi, spi);
> +
> + return 0;
> +}
...
> + readb_poll_timeout(loongson_spi->base + LOONGSON_SPI_SPSR_REG, loongson_spi->spsr,
> + (loongson_spi->spsr & 0x1) != 1, 1, MSEC_PER_SEC);
Wouldn't be better to use ' == 0' in the conditional? Or if you think your
approach is better (to show the exact expectation) the definition of the bit 0
might help
#define LOONGSON_... BIT(0)
readb_poll_timeout(loongson_spi->base + LOONGSON_SPI_SPSR_REG, loongson_spi->spsr,
(loongson_spi->spsr & LOONGSON_...) != LOONGSON_...,
1, MSEC_PER_SEC);
...
> + do {
> + if (loongson_spi_write_read_8bit(spi, &tx, &rx, count) < 0)
> + goto out;
break;
> + count--;
> + } while (count);
} while (--count);
?
> +out:
> + return xfer->len - count;
Shouldn't you return an error code if the write failed?
...
> + master = devm_spi_alloc_master(dev, sizeof(struct loongson_spi));
> + if (master == NULL)
if (!master)
> + return -ENOMEM;
Why do you use deprecated naming? Can you use spi_controller* instead of
spi_master* in all cases?
...
> + master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
= SPI_MODE_X_MASK | SPI_CS_HIGH;
...
> + clk = devm_clk_get_optional(dev, NULL);
> + if (!IS_ERR(clk))
> + spi->clk_rate = clk_get_rate(clk);
> + else
Redundant. Just check for the error first as it's very usual pattern in the
Linux kernel.
> + return dev_err_probe(dev, PTR_ERR(clk), "unable to get clock\n");
...
> +static void loongson_spi_pci_unregister(struct pci_dev *pdev)
> +{
> + pcim_iounmap_regions(pdev, BIT(0));
Not needed due to 'm' in the API name, which means "managed".
> + pci_disable_device(pdev);
This is simply wrong. We don't do explicit clean up for managed resources.
> +}
That said, drop the ->remove() completely.
...
> +static struct pci_device_id loongson_spi_devices[] = {
> + { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x7a0b) },
> + { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x7a1b) },
> + { },
No comma for the terminator entry. It's by definition "terminating" something.
> +};
...
> +#include <linux/of.h>
There is no user of this header. Please, replace with what actually is being
used (presumably mod_devicetable.h and maybe others).
> +#include <linux/platform_device.h>
> +
> +#include "spi-loongson.h"
> +
> +static int loongson_spi_platform_probe(struct platform_device *pdev)
> +{
> + int ret;
> + void __iomem *reg_base;
> + struct device *dev = &pdev->dev;
> +
> + reg_base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(reg_base))
> + return PTR_ERR(reg_base);
> +
> + ret = loongson_spi_init_master(dev, reg_base);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to initialize master\n");
> +
> + return ret;
return 0;
> +}
...
> +#ifndef __LINUX_SPI_LOONGSON_H
> +#define __LINUX_SPI_LOONGSON_H
> +
> +#include <linux/bits.h>
> +#include <linux/device.h>
This header is not used.
> +#include <linux/pm.h>
> +#include <linux/spi/spi.h>
This neither.
> +#include <linux/types.h>
For them use forward declarations
struct device;
struct spi_controller;
The rest of the inclusions is correct.
...
> +#define LOONGSON_SPI_SPCR_REG 0x00
> +#define LOONGSON_SPI_SPSR_REG 0x01
> +#define LOONGSON_SPI_FIFO_REG 0x02
> +#define LOONGSON_SPI_SPER_REG 0x03
> +#define LOONGSON_SPI_PARA_REG 0x04
> +#define LOONGSON_SPI_SFCS_REG 0x05
> +#define LOONGSON_SPI_TIMI_REG 0x06
Where is this used outside of the main driver?
> +/* Bits definition for Loongson SPI register */
> +#define LOONGSON_SPI_PARA_MEM_EN BIT(0)
> +#define LOONGSON_SPI_SPCR_CPHA BIT(2)
> +#define LOONGSON_SPI_SPCR_CPOL BIT(3)
> +#define LOONGSON_SPI_SPCR_SPE BIT(6)
> +#define LOONGSON_SPI_SPSR_WCOL BIT(6)
> +#define LOONGSON_SPI_SPSR_SPIF BIT(7)
> +
> +struct loongson_spi {
> + struct spi_master *master;
> + void __iomem *base;
> + int cs_active;
> + unsigned int hz;
> + unsigned char spcr;
> + unsigned char sper;
> + unsigned char spsr;
> + unsigned char para;
> + unsigned char sfcs;
> + unsigned char timi;
> + unsigned int mode;
> + u64 clk_rate;
> +};
> +
> +int loongson_spi_init_master(struct device *dev, void __iomem *reg);
> +extern const struct dev_pm_ops loongson_spi_dev_pm_ops;
> +#endif /* __LINUX_SPI_LOONGSON_H */
--
With Best Regards,
Andy Shevchenko
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