Re: [PATCH] Topcliff PHUB: Generate PacketHub driver

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

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@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

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.