Messages in this thread | | | Subject | Re: [PATCH v11 2/2] spi: loongson: add bus driver for the loongson spi controller | From | zhuyinbo <> | Date | Wed, 24 May 2023 15:52:18 +0800 |
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在 2023/5/23 下午8:54, andy.shevchenko@gmail.com 写道: > 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.
okay, I got it. > > ... > >> +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?
okay, I will define "static const char rdiv".
> >> + >> + 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 ...`)
I alwasy use `make W=1` and I don't find any warnig, but that what you said was right and I will initial hz.
> >> + 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)
okay, I got it. > > > 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); > > ?
okay, I got it.
> >> +out: >> + return xfer->len - count; > > Shouldn't you return an error code if the write failed?
okay, I got it. I will add a error code for return when 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?
It seems was a personal code style issue and I don't find the differences between spi_controller and spi_master, Using spi_controller* is also acceptable to me and I will 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.
Like below ?
clk = devm_clk_get_optional(dev, NULL); - if (!IS_ERR(clk)) - spi->clk_rate = clk_get_rate(clk); - else + if (IS_ERR(clk)) return dev_err_probe(dev, PTR_ERR(clk), "unable to get clock\n");
+ spi->clk_rate = clk_get_rate(clk); loongson_spi_reginit(spi);
> >> + 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.
okay, I will 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.
okay, I got it. > >> +}; > > ... > >> +#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). >
okay, I got it.
>> +#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;
It seems was more appropriate that initialize ret then return ret. Do you think so ?
> >> +} > > ... > >> +#ifndef __LINUX_SPI_LOONGSON_H >> +#define __LINUX_SPI_LOONGSON_H >> + >> +#include <linux/bits.h> > >> +#include <linux/device.h> > > This header is not used.
okay, I got it. > >> +#include <linux/pm.h> > >> +#include <linux/spi/spi.h> > > This neither.
That other .c file seems to need it and I will move it to other .c code file. > >> +#include <linux/types.h> > > > For them use forward declarations > > struct device; > struct spi_controller; > > The rest of the inclusions is correct.
okay, I got it. > > ... > >> +#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?
These definitions are only used in core.c
> >> +/* 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 */ >
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