Hi Matt,
On Thu, 18 Aug 2011 19:43:11 -0400, Matt Turner wrote:
> From: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
>
> This is a rewrite of large parts of the driver mainly so that it uses
> SMBus interrupts to offload the CPU from busy-waiting on status inputs.
> As a part of the overhaul of the init and exit calls, all accesses to the
> hardware got converted to use accessory functions via an ioremap() cookie.
This could have been split into incremental patches, to make review
easier.
> [mattst88] Added BCM1480 interrupts and rebased minimally.
Ditto.
checkpatch complains about this, please fix:
WARNING: line over 80 characters
#257: FILE: drivers/i2c/busses/i2c-sibyte.c:157:
+ if (adap->status > 0 && ((adap->status & (M_SMB_ERROR | M_SMB_ERROR_TYPE)) == M_SMB_ERROR)) {
Very nice patch overall, I only have minor comments, see below inline.
>
> Signed-off-by: Matt Turner <mattst88@xxxxxxxxx>
> Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
> ---
> This is the second version of this patch that I've sent. This version
> fixes the problem with the ENXIO return.
>
> drivers/i2c/busses/i2c-sibyte.c | 296 +++++++++++++++++++++++++++++---------
> 1 files changed, 226 insertions(+), 70 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-sibyte.c b/drivers/i2c/busses/i2c-sibyte.c
> index 0fe505d..d2f1cf1 100644
> --- a/drivers/i2c/busses/i2c-sibyte.c
> +++ b/drivers/i2c/busses/i2c-sibyte.c
> @@ -2,6 +2,7 @@
> * Copyright (C) 2004 Steven J. Hill
> * Copyright (C) 2001,2002,2003 Broadcom Corporation
> * Copyright (C) 1995-2000 Simon G. Vogl
> + * Copyright (C) 2008 Maciej W. Rozycki
Wow, looks like this patch has been sleeping for quite some time...
> *
> * This program is free software; you can redistribute it and/or
> * modify it under the terms of the GNU General Public License
> @@ -18,104 +19,164 @@
> * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
> */
>
> +#include <linux/errno.h>
> +#include <linux/interrupt.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/i2c.h>
> +#include <linux/param.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +#include <linux/wait.h>
> #include <linux/io.h>
> +#include <asm/sibyte/sb1250_int.h>
> #include <asm/sibyte/sb1250_regs.h>
> #include <asm/sibyte/sb1250_smbus.h>
> +#include <asm/sibyte/bcm1480_int.h>
>
>
> struct i2c_algo_sibyte_data {
> - void *data; /* private data */
> - int bus; /* which bus */
> - void *reg_base; /* CSR base */
> + wait_queue_head_t wait; /* IRQ queue */
> + void __iomem *csr; /* mapped CSR handle */
> + phys_t base; /* physical CSR base */
> + char *name; /* IRQ handler name */
Should be a const pointer. Also, if the name is only for the IRQ, then
irq_name would be a better name.
> + spinlock_t lock; /* atomiser */
A more useful comment would explain what exactly is being protected by
the lock.
> + int irq; /* IRQ line */
> + int status; /* IRQ status */
You could document than -1 means error.
> };
>
> -/* ----- global defines ----------------------------------------------- */
> -#define SMB_CSR(a,r) ((long)(a->reg_base + r))
>
> +static irqreturn_t i2c_sibyte_interrupt(int irq, void *dev_id)
> +{
> + struct i2c_adapter *i2c_adap = dev_id;
> + struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;
> + void __iomem *csr = adap->csr;
> + u8 status;
> +
> + /*
> + * Ugh, no way to detect the finish interrupt,
> + * but if busy it is obviously not one.
> + */
> + status = __raw_readq(csr + R_SMB_STATUS);
> + if ((status & (M_SMB_ERROR | M_SMB_BUSY)) == M_SMB_BUSY)
> + return IRQ_NONE;
> +
> + /*
> + * Clear the error interrupt (write 1 to clear);
> + * the finish interrupt was cleared by the read above.
> + */
> + __raw_writeq(status, csr + R_SMB_STATUS);
> +
> + /* Post the status. */
> + spin_lock(&adap->lock);
> + adap->status = status & (M_SMB_ERROR_TYPE | M_SMB_ERROR | M_SMB_BUSY);
> + wake_up(&adap->wait);
> + spin_unlock(&adap->lock);
> +
> + return IRQ_HANDLED;
> +}
>
> -static int smbus_xfer(struct i2c_adapter *i2c_adap, u16 addr,
> - unsigned short flags, char read_write,
> - u8 command, int size, union i2c_smbus_data * data)
> +static s32 i2c_sibyte_smbus_xfer(struct i2c_adapter *i2c_adap, u16 addr,
> + unsigned short cflags,
> + char read_write, u8 command, int size,
> + union i2c_smbus_data *data)
> {
> struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;
> + void __iomem *csr = adap->csr;
> + unsigned long flags;
> int data_bytes = 0;
> int error;
>
> - while (csr_in32(SMB_CSR(adap, R_SMB_STATUS)) & M_SMB_BUSY)
> - ;
> + spin_lock_irqsave(&adap->lock, flags);
> +
> + if (adap->status < 0) {
> + error = -EIO;
> + goto out_unlock;
> + }
Well, this can only happen if the previous transaction ended up with a
failure, right? This means that a single error will break the SMBus
forever. Is there no way to reset the controller to a sane state if
this happens?
>
> switch (size) {
> case I2C_SMBUS_QUICK:
> - csr_out32((V_SMB_ADDR(addr) |
> - (read_write == I2C_SMBUS_READ ? M_SMB_QDATA : 0) |
> - V_SMB_TT_QUICKCMD), SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_ADDR(addr) |
> + (read_write == I2C_SMBUS_READ ? M_SMB_QDATA : 0) |
> + V_SMB_TT_QUICKCMD,
> + csr + R_SMB_START);
> break;
> case I2C_SMBUS_BYTE:
> if (read_write == I2C_SMBUS_READ) {
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_RD1BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_RD1BYTE,
> + csr + R_SMB_START);
> data_bytes = 1;
> } else {
> - csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR1BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_CMD(command), csr + R_SMB_CMD);
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_WR1BYTE,
> + csr + R_SMB_START);
> }
> break;
> case I2C_SMBUS_BYTE_DATA:
> - csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
> + __raw_writeq(V_SMB_CMD(command), csr + R_SMB_CMD);
> if (read_write == I2C_SMBUS_READ) {
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD1BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD1BYTE,
> + csr + R_SMB_START);
> data_bytes = 1;
> } else {
> - csr_out32(V_SMB_LB(data->byte),
> - SMB_CSR(adap, R_SMB_DATA));
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_LB(data->byte), csr + R_SMB_DATA);
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE,
> + csr + R_SMB_START);
> }
> break;
> case I2C_SMBUS_WORD_DATA:
> - csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
> + __raw_writeq(V_SMB_CMD(command), csr + R_SMB_CMD);
> if (read_write == I2C_SMBUS_READ) {
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD2BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD2BYTE,
> + csr + R_SMB_START);
> data_bytes = 2;
> } else {
> - csr_out32(V_SMB_LB(data->word & 0xff),
> - SMB_CSR(adap, R_SMB_DATA));
> - csr_out32(V_SMB_MB(data->word >> 8),
> - SMB_CSR(adap, R_SMB_DATA));
> - csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE),
> - SMB_CSR(adap, R_SMB_START));
> + __raw_writeq(V_SMB_LB(data->word & 0xff),
> + csr + R_SMB_DATA);
> + __raw_writeq(V_SMB_MB(data->word >> 8),
> + csr + R_SMB_DATA);
> + __raw_writeq(V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE,
> + csr + R_SMB_START);
> }
> break;
> default:
> - return -EOPNOTSUPP;
> + error = -EOPNOTSUPP;
> + goto out_unlock;
> }
> + mmiowb();
> + __raw_readq(csr + R_SMB_START);
> + adap->status = -1;
> +
> + spin_unlock_irqrestore(&adap->lock, flags);
>
> - while (csr_in32(SMB_CSR(adap, R_SMB_STATUS)) & M_SMB_BUSY)
> - ;
> + wait_event_timeout(adap->wait, (adap->status >= 0), HZ);
1 second is a rather long timeout. The driver only supports small
transactions, so even if a slave slows down the clock, I can hardly
imagine a transaction lasting more that, say, 10 ms. So I think you can
safely lower the timeout to HZ / 5 or even HZ / 10.
Also, shouldn't you check the return value? This would let you return
the right error code (-ETIMEDOUT according to
Documentation/i2c/fault-codes) and you would no longer have to check
for adap->status sign in the rest of the function.
>
> - error = csr_in32(SMB_CSR(adap, R_SMB_STATUS));
> - if (error & M_SMB_ERROR) {
> - /* Clear error bit by writing a 1 */
> - csr_out32(M_SMB_ERROR, SMB_CSR(adap, R_SMB_STATUS));
> - return (error & M_SMB_ERROR_TYPE) ? -EIO : -ENXIO;
> + spin_lock_irqsave(&adap->lock, flags);
> +
> + if (adap->status > 0 && ((adap->status & (M_SMB_ERROR | M_SMB_ERROR_TYPE)) == M_SMB_ERROR)) {
> + error = -ENXIO;
> + goto out_unlock;
> + }
> + if (adap->status < 0 || (adap->status & (M_SMB_ERROR | M_SMB_BUSY))) {
> + error = -EIO;
> + goto out_unlock;
> }
>
> if (data_bytes == 1)
> - data->byte = csr_in32(SMB_CSR(adap, R_SMB_DATA)) & 0xff;
> + data->byte = __raw_readq(csr + R_SMB_DATA) & 0xff;
> if (data_bytes == 2)
> - data->word = csr_in32(SMB_CSR(adap, R_SMB_DATA)) & 0xffff;
> + data->word = __raw_readq(csr + R_SMB_DATA) & 0xffff;
>
> - return 0;
> + error = 0;
> +
> +out_unlock:
> + spin_unlock_irqrestore(&adap->lock, flags);
> +
> + return error;
> }
>
> -static u32 bit_func(struct i2c_adapter *adap)
> +static u32 i2c_sibyte_bit_func(struct i2c_adapter *adap)
If you're renaming this then please drop the "bit" part in it, it's
most likely coming from a copy-and-paste from i2c-algo-bit and has no
meaning in the sibyte driver.
> {
> return (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA);
> @@ -125,8 +186,8 @@ static u32 bit_func(struct i2c_adapter *adap)
> /* -----exported algorithm data: ------------------------------------- */
>
> static const struct i2c_algorithm i2c_sibyte_algo = {
> - .smbus_xfer = smbus_xfer,
> - .functionality = bit_func,
> + .smbus_xfer = i2c_sibyte_smbus_xfer,
> + .functionality = i2c_sibyte_bit_func,
> };
>
> /*
> @@ -135,37 +196,121 @@ static const struct i2c_algorithm i2c_sibyte_algo = {
> static int __init i2c_sibyte_add_bus(struct i2c_adapter *i2c_adap, int speed)
> {
> struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;
> + void __iomem *csr;
> + int err;
>
> - /* Register new adapter to i2c module... */
> - i2c_adap->algo = &i2c_sibyte_algo;
> + adap->status = 0;
> + init_waitqueue_head(&adap->wait);
> + spin_lock_init(&adap->lock);
> +
> + csr = ioremap(adap->base, R_SMB_PEC + SMB_REGISTER_SPACING);
> + if (!csr) {
> + err = -ENOMEM;
> + goto out;
> + }
> + adap->csr = csr;
>
> /* Set the requested frequency. */
> - csr_out32(speed, SMB_CSR(adap,R_SMB_FREQ));
> - csr_out32(0, SMB_CSR(adap,R_SMB_CONTROL));
> + __raw_writeq(speed, csr + R_SMB_FREQ);
> +
> + /* Clear any pending error interrupt. */
> + __raw_writeq(__raw_readq(csr + R_SMB_STATUS), csr + R_SMB_STATUS);
> + /* Disable interrupts. */
> + __raw_writeq(0, csr + R_SMB_CONTROL);
> + mmiowb();
> + __raw_readq(csr + R_SMB_CONTROL);
Shouldn't it be the other way around, disable interrupts first and then
clear any pending one? Looks racy otherwise, but maybe it makes no
difference in practice.
> +
> + err = request_irq(adap->irq, i2c_sibyte_interrupt, IRQF_SHARED,
> + adap->name, i2c_adap);
> + if (err < 0)
> + goto out_unmap;
> +
> + /* Enable finish and error interrupts. */
> + __raw_writeq(M_SMB_FINISH_INTR | M_SMB_ERR_INTR, csr + R_SMB_CONTROL);
> +
> + /* Register new adapter to i2c module... */
> + err = i2c_add_numbered_adapter(i2c_adap);
> + if (err < 0)
> + goto out_unirq;
> +
> + return 0;
>
> - return i2c_add_numbered_adapter(i2c_adap);
> +out_unirq:
> + /* Disable interrupts. */
> + __raw_writeq(0, csr + R_SMB_CONTROL);
> + mmiowb();
> + __raw_readq(csr + R_SMB_CONTROL);
> +
> + free_irq(adap->irq, i2c_adap);
> +
> + /* Clear any pending error interrupt. */
> + __raw_writeq(__raw_readq(csr + R_SMB_STATUS), csr + R_SMB_STATUS);
You may consider moving this block to a separate function, as it is
duplicated in the i2c_sibyte_remove_bus() function below.
> +out_unmap:
> + iounmap(csr);
> +out:
> + return err;
> }
>
> +static void i2c_sibyte_remove_bus(struct i2c_adapter *i2c_adap)
> +{
> + struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;
> + void __iomem *csr = adap->csr;
> +
> + i2c_del_adapter(i2c_adap);
> +
> + /* Disable interrupts. */
> + __raw_writeq(0, csr + R_SMB_CONTROL);
> + mmiowb();
> + __raw_readq(csr + R_SMB_CONTROL);
>
> -static struct i2c_algo_sibyte_data sibyte_board_data[2] = {
> - { NULL, 0, (void *) (CKSEG1+A_SMB_BASE(0)) },
> - { NULL, 1, (void *) (CKSEG1+A_SMB_BASE(1)) }
> + free_irq(adap->irq, i2c_adap);
> +
> + /* Clear any pending error interrupt. */
> + __raw_writeq(__raw_readq(csr + R_SMB_STATUS), csr + R_SMB_STATUS);
> +
> + iounmap(csr);
> +}
> +
> +static struct i2c_algo_sibyte_data i2c_sibyte_board_data[2] = {
> +#ifdef CONFIG_SIBYTE_SB1250
> + {
> + .name = "sb1250-smbus-0",
> + .base = A_SMB_0,
> + .irq = K_INT_SMB_0,
> + },
> + {
> + .name = "sb1250-smbus-1",
> + .base = A_SMB_1,
> + .irq = K_INT_SMB_1,
> + }
> +#else
> + {
> + .name = "bcm1480-smbus-0",
> + .base = A_SMB_0,
> + .irq = K_BCM1480_INT_SMB_0,
> + },
> + {
> + .name = "bcm1480-smbus-1",
> + .base = A_SMB_1,
> + .irq = K_BCM1480_INT_SMB_1,
> + }
> +#endif
> };
>
> -static struct i2c_adapter sibyte_board_adapter[2] = {
> +static struct i2c_adapter i2c_sibyte_board_adapter[2] = {
> {
> .owner = THIS_MODULE,
> .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
> - .algo = NULL,
> - .algo_data = &sibyte_board_data[0],
> + .algo = &i2c_sibyte_algo,
> + .algo_data = &i2c_sibyte_board_data[0],
> .nr = 0,
> .name = "SiByte SMBus 0",
> },
> {
> .owner = THIS_MODULE,
> .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
> - .algo = NULL,
> - .algo_data = &sibyte_board_data[1],
> + .algo = &i2c_sibyte_algo,
> + .algo_data = &i2c_sibyte_board_data[1],
> .nr = 1,
> .name = "SiByte SMBus 1",
> },
> @@ -173,21 +318,32 @@ static struct i2c_adapter sibyte_board_adapter[2] = {
>
> static int __init i2c_sibyte_init(void)
> {
> + int err;
> +
> pr_info("i2c-sibyte: i2c SMBus adapter module for SiByte board\n");
> - if (i2c_sibyte_add_bus(&sibyte_board_adapter[0], K_SMB_FREQ_100KHZ) < 0)
> - return -ENODEV;
> - if (i2c_sibyte_add_bus(&sibyte_board_adapter[1],
> - K_SMB_FREQ_400KHZ) < 0) {
> - i2c_del_adapter(&sibyte_board_adapter[0]);
> - return -ENODEV;
> - }
> +
> + err = i2c_sibyte_add_bus(&i2c_sibyte_board_adapter[0],
> + K_SMB_FREQ_100KHZ);
> + if (err < 0)
> + goto out;
> +
> + err = i2c_sibyte_add_bus(&i2c_sibyte_board_adapter[1],
> + K_SMB_FREQ_400KHZ);
> + if (err < 0)
> + goto out_remove;
> +
> return 0;
> +
> +out_remove:
> + i2c_sibyte_remove_bus(&i2c_sibyte_board_adapter[0]);
> +out:
> + return err;
> }
>
> static void __exit i2c_sibyte_exit(void)
> {
> - i2c_del_adapter(&sibyte_board_adapter[0]);
> - i2c_del_adapter(&sibyte_board_adapter[1]);
> + i2c_sibyte_remove_bus(&i2c_sibyte_board_adapter[1]);
> + i2c_sibyte_remove_bus(&i2c_sibyte_board_adapter[0]);
> }
>
> module_init(i2c_sibyte_init);
Please address my concerns where you agree and send an updated patch.
--
Jean Delvare
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