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Date: Tue, 08 Jun 2010 14:00:55 +0900
From: Masayuki Ohtak <masa-korg@....okisemi.com>
To: "Alan Cox" <alan@...rguk.ukuu.org.uk>
CC: "LKML" <linux-kernel@...r.kernel.org>,
"Andrew" <andrew.chih.howe.khor@...el.com>,
"Intel OTC" <joel.clark@...el.com>, "Wang, Qi" <qi.wang@...el.com>,
"Wang, Yong Y" <yong.y.wang@...el.com>,
"Masayuki Ohtak" <masa-korg@....okisemi.com>
Subject: Re: [PATCH] Topcliff PHUB: Generate PacketHub driver
Hi Alan
We are now updating our Phub driver.
I have a questions for your comment.
(1)
>> +#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
We couldn't understand your intention.
Does the above mean we must not use "#ifdef PCH_CAN_PCLK_50MHZ" in source code ?
BTW, We show our modification policy the following email with inline.
Please confirm it.
If there is any mistake, please inform us.
Thanks.
Ohtake.
----- Original Message -----
From: "Alan Cox" <alan@...rguk.ukuu.org.uk>
To: "Masayuki Ohtak" <masa-korg@....okisemi.com>
Cc: "LKML" <linux-kernel@...r.kernel.org>; "Andrew" <andrew.chih.howe.khor@...el.com>; "Intel OTC" <joel.clark@...el.com>; "Wang, Qi" <qi.wang@...el.com>; "Wang, Yong Y" <yong.y.wang@...el.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
The above brackets are deleted
>
>> +#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)
Modify like below.
#define PCH_READ_REG(a) ioread32(pch_phub_base_address + (a))
#define PCH_WRITE_REG(a, b) iowrite32(a, pch_phub_base_address + (b))
>
>
>> +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_
Delete prefix '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 ?
Move the above 4 variables into 'struct pch_phub_reg_t'.
>> +
>> +struct device *dev_dbg;
>
> Not a good name for a global variable as it will clash with others
Modify to phub_dev_dbg.
>
>> +DEFINE_SPINLOCK(pch_phub_lock); /* for spin lock */
>
> Can this be static or in the struct ?
Modify lile below.
static DEFINE_SPINLOCK(pch_phub_lock); /* for spin lock */
>
>> +
>> +/**
>> + * 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 ?
>
Modify to 'static const'.
>> +/*--------------------------------------------
>> + exported function prototypes
>> +--------------------------------------------*/
>
> They start 'static' I don't think they are exportdd !
Modify comment to 'Internal function prototypes'
>
>> +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 ?
Move the PCI registration code to the bottom of the file.
>
>> +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
reg_addr/pch_phub_base_address are defined as 'void __iomem',
>
>> +#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 ?
Delete '=0'
>
>> +/** 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
Please refer the above.(defined as 'void __iomem',)
>
>
>
>> +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
Modify like belwo,
u64 addr_offset;
>
>> + 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
The above copy_from_user is Copy global variable to local variable.
Thus, We think this code has re-entrant.
>
>> +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.
Modify type of addr_offset to u64
>
>> +};
>> +
>> +/* 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
Add static description for all of internal functions.
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