Re: [PATCH] Topcliff PHUB: Generate PacketHub driver

["Masayuki Ohtake" <masa-korg@dsn.okisemi.com>]

Hi Alan,

Thank you for your comments.
We will integrate your comments to our PHUB by today or tomorrow at the latest.

Ohtake.
----- Original Message ----- 
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
To: "Masayuki Ohtak" <masa-korg@dsn.okisemi.com>
Cc: "LKML" <linux-kernel@vger.kernel.org>; "Andrew" <andrew.chih.howe.khor@intel.com>; "Intel OTC"
<joel.clark@intel.com>; "Wang, Qi" <qi.wang@intel.com>; "Wang, Yong Y" <yong.y.wang@intel.com>
Sent: Tuesday, June 08, 2010 12:05 AM
Subject: Re: [PATCH] Topcliff PHUB: Generate PacketHub driver


> O> +/* Status Register offset */
> > +#define PHUB_STATUS (0x00)
> > +/* Control Register offset */
> > +#define PHUB_CONTROL (0x04)
> > +/* Time out value for Status Register */
> > +#define PHUB_TIMEOUT (0x05)
> > +/* Enabling for writing ROM */
> > +#define PCH_PHUB_ROM_WRITE_ENABLE (0x01)
> > +/* Disabling for writing ROM */
> > +#define PCH_PHUB_ROM_WRITE_DISABLE (0x00)
> > +/* ROM data area start address offset */
> > +#define PCH_PHUB_ROM_START_ADDR (0x14)
> > +/* MAX number of INT_REDUCE_CONTROL registers */
> > +#define MAX_NUM_INT_REDUCE_CONTROL_REG (128)
> > +
> > +#define PCI_DEVICE_ID_PCH1_PHUB (0x8801)
> > +
> > +#define PCH_MINOR_NOS (1)
> > +#define CLKCFG_CAN_50MHZ (0x12000000)
> > +#define CLKCFG_CANCLK_MASK (0xFF000000)
>
> Style: constants don't need brackets - might also look more Linux like
> tabbed out a bit
>
> > +#define PCH_READ_REG(a) ioread32((pch_phub_base_address + a))
> > +
> > +#define PCH_WRITE_REG(a, b) iowrite32(a, (pch_phub_base_address + b))
>
> These on the other hand do - but not where they are now
>
> iowrite32((a), pcb_phub_base_address + (b))
>
> (so that if a or b are expressions they are evaluated first)
>
>
> > +struct pch_phub_reg {
> > + u32 phub_id_reg; /* PHUB_ID register val */
> > + u32 q_pri_val_reg; /* QUEUE_PRI_VAL register val */
> > + u32 rc_q_maxsize_reg; /* RC_QUEUE_MAXSIZE register val */
> > + u32 bri_q_maxsize_reg; /* BRI_QUEUE_MAXSIZE register val */
> > + u32 comp_resp_timeout_reg; /* COMP_RESP_TIMEOUT register val */
> > + u32 bus_slave_control_reg; /* BUS_SLAVE_CONTROL_REG register val */
> > + u32 deadlock_avoid_type_reg; /* DEADLOCK_AVOID_TYPE register val */
> > + u32 intpin_reg_wpermit_reg0; /* INTPIN_REG_WPERMIT register 0 val */
> > + u32 intpin_reg_wpermit_reg1; /* INTPIN_REG_WPERMIT register 1 val */
> > + u32 intpin_reg_wpermit_reg2; /* INTPIN_REG_WPERMIT register 2 val */
> > + u32 intpin_reg_wpermit_reg3; /* INTPIN_REG_WPERMIT register 3 val */
> > + /* INT_REDUCE_CONTROL registers val */
> > + u32 int_reduce_control_reg[MAX_NUM_INT_REDUCE_CONTROL_REG];
> > +#ifdef PCH_CAN_PCLK_50MHZ
> > + u32 clkcfg_reg; /* CLK CFG register val */
> > +#endif
> > +} g_pch_phub_reg;
>
> Stylewise the kernel doesn't use the g_ convention that many Windows
> people do, so lose the g_
>
> > +s32 pch_phub_opencount; /* check whether opened or not */
> > +u32 pch_phub_base_address;
> > +u32 pch_phub_extrom_base_address;
> > +s32 pch_phub_suspended;
>
> Any reason these can't be in the struct ?
> > +
> > +struct device *dev_dbg;
>
> Not a good name for a global variable as it will clash with others
>
> > +DEFINE_SPINLOCK(pch_phub_lock); /* for spin lock */
>
> Can this be static or in the struct ?
>
> > +
> > +/**
> > + * file_operations structure initialization
> > + */
> > +const struct file_operations pch_phub_fops = {
> > + .owner = THIS_MODULE,
> > + .open = pch_phub_open,
> > + .release = pch_phub_release,
> > + .ioctl = pch_phub_ioctl,
> > +};
>
> static const ?
>
> > +/*--------------------------------------------
> > + exported function prototypes
> > +--------------------------------------------*/
>
> They start 'static' I don't think they are exportdd !
>
> > +static int __devinit pch_phub_probe(struct pci_dev *pdev, const
> > +        struct pci_device_id *id);
> > +static void __devexit pch_phub_remove(struct pci_dev *pdev);
> > +static int pch_phub_suspend(struct pci_dev *pdev, pm_message_t state);
> > +static int pch_phub_resume(struct pci_dev *pdev);
>
> > +static struct pci_driver pch_phub_driver = {
> > + .name = "pch_phub",
> > + .id_table = pch_phub_pcidev_id,
> > + .probe = pch_phub_probe,
> > + .remove = __devexit_p(pch_phub_remove),
> > +#ifdef CONFIG_PM
> > + .suspend = pch_phub_suspend,
> > + .resume = pch_phub_resume
> > +#endif
> > +};
> > +
> > +static int __init pch_phub_pci_init(void);
> > +static void __exit pch_phub_pci_exit(void);
> > +
> > +MODULE_DESCRIPTION("PCH PACKET HUB PCI Driver");
> > +MODULE_LICENSE("GPL");
> > +module_init(pch_phub_pci_init);
> > +module_exit(pch_phub_pci_exit);
> > +module_param(pch_phub_major_no, int, S_IRUSR | S_IWUSR);
>
> If you migrated the module registration/PCI registration to the bottom of
> the file you could avoid the forward declations and make the code easier
> to follow ?
>
> > +void pch_phub_read_modify_write_reg(unsigned long reg_addr_offset,
> > +        unsigned long data, unsigned long mask)
> > +{
> > + unsigned long reg_addr = pch_phub_base_address + reg_addr_offset;
> > + iowrite32(((ioread32((void __iomem *)reg_addr) & ~mask)) | data,
> > + (void __iomem *)reg_addr);
>
> When you have that many casts in a line it's perhaps a hint you have the
> types wrong initially. At the very least reg_addr should be void __iomem,
> and probably pch_phub_base_address should be
>
> It would probably make sense to pass a pointer to your struct pch_hub_reg
> and use that to hold the base address. Then if you ever get a box with
> two in some future design it won't be a disaster
>
> > +void pch_phub_save_reg_conf(void)
>
> Ditto
>
> > +#ifdef PCH_CAN_PCLK_50MHZ
> > + /* save clk cfg register */
> > + g_pch_phub_reg.clkcfg_reg = PCH_READ_REG(CLKCFG_REG_OFFSET);
> > +#endif
>
> This makes it hard to build one kernel for everything
>
> > + return;
> > +}
>
> > +void pch_phub_restore_reg_conf(void)
> > +{
> > + u32 i = 0;
>
> Why = 0, if you do that here you may hide initialisation errors from
> future changes ?
>
> > +/** pch_phub_read_serial_rom - Implements the functionality of reading Serial
> > + *  ROM.
> > + *  @offset_address: Contains the Serial ROM address offset value
> > + *  @data: Contains the Serial ROM value
> > + */
> > +int pch_phub_read_serial_rom(unsigned long offset_address, unsigned char *data)
> > +{
> > + unsigned long mem_addr = pch_phub_extrom_base_address + offset_address;
> > +
> > + dev_dbg(dev_dbg,
> > + "pch_phub_read_serial_rom:mem_addr=0x%08x\n", (u32)mem_addr);
> > + *data = ioread8((void __iomem *)mem_addr);
>
> Same comments about casts
>
>
>
> > +int pch_phub_ioctl(struct inode *inode, struct file *file,
> > + unsigned int cmd, unsigned long arg)
> > +{
> > + int ret_value = 0;
> > + struct pch_phub_reqt *p_pch_phub_reqt;
> > + unsigned long addr_offset;
>
> This will change size on 32/64bit boxes makign your copy a bit
> problematic
>
> > + p_pch_phub_reqt = (struct pch_phub_reqt *)arg;
> > + ret_value = copy_from_user((void *)&addr_offset,
> > + (void *)&p_pch_phub_reqt->addr_offset,
> > + sizeof(addr_offset));
> > + if (ret_value) {
>
> > + /* End of Access area check */
>
> Remember here ioctl isn't single threaded so you may want to double check
> some of these
>
> > +struct pch_phub_reqt {
> > + unsigned long addr_offset; /*specifies the register address
> > + offset */
> > + unsigned long data; /*specifies the data */
> > + unsigned long mask; /*specifies the mask */
>
> If they may need to be long make them u64. That way 32 and 64bit systems
> get the same ioctl structure and life is good.
>
> > +};
> > +
> > +/* exported function prototypes */
> > +int pch_phub_open(struct inode *inode, struct file *file);
> > +int pch_phub_release(struct inode *inode, struct file *file);
> > +int pch_phub_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
> > +       unsigned long arg);
>
> You have various other functions that are not static - if they should be
> then make them static
>
> Alan
>