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Message-ID: <20150721212455.GA7565@mail.corp.redhat.com>
Date: Tue, 21 Jul 2015 17:24:55 -0400
From: Benjamin Tissoires <benjamin.tissoires@...il.com>
To: Wolfram Sang <wsa@...-dreams.de>, Jean Delvare <jdelvare@...e.de>,
Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] i2c: i801: add support of Host Notify
On Jul 09 2015 or thereabouts, Benjamin Tissoires wrote:
> The i801 chip can handle the Host Notify feature since ICH 3 as mentioned
> in http://www.intel.com/content/dam/doc/datasheet/82801ca-io-controller-hub-3-datasheet.pdf
>
> Enable the functionality unconditionally and propagate the alert
> on each notification.
>
> With a T440s and a Synaptics touchpad that implements Host Notify, the
> payload data is always 0x0000, so I am not sure if the device actually
> sends the payload or if there is a problem regarding the implementation.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
>
> Changes in v2:
> - removed the description of the Slave functionality support in the chip table
> (the table shows what is supported, not what the hardware is capable of)
> - use i2c-smbus to forward the notification
> - remove the fifo, and directly retrieve the address and payload in the worker
> - do not check for Host Notification is the feature is not enabled
> - use inw_p() to read the payload instead of 2 inb_p() calls
> - add /* fall-through */ comment
> - unconditionally enable Host Notify if the hardware supports it (can be
> disabled by the user)
>
> drivers/i2c/busses/i2c-i801.c | 172 +++++++++++++++++++++++++++++++-----------
> 1 file changed, 129 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index 5ecbb3f..f65f955 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -20,46 +20,46 @@
> /*
> * Supports the following Intel I/O Controller Hubs (ICH):
> *
> - * I/O Block I2C
> - * region SMBus Block proc. block
> - * Chip name PCI ID size PEC buffer call read
> - * ---------------------------------------------------------------------------
> - * 82801AA (ICH) 0x2413 16 no no no no
> - * 82801AB (ICH0) 0x2423 16 no no no no
> - * 82801BA (ICH2) 0x2443 16 no no no no
> - * 82801CA (ICH3) 0x2483 32 soft no no no
> - * 82801DB (ICH4) 0x24c3 32 hard yes no no
> - * 82801E (ICH5) 0x24d3 32 hard yes yes yes
> - * 6300ESB 0x25a4 32 hard yes yes yes
> - * 82801F (ICH6) 0x266a 32 hard yes yes yes
> - * 6310ESB/6320ESB 0x269b 32 hard yes yes yes
> - * 82801G (ICH7) 0x27da 32 hard yes yes yes
> - * 82801H (ICH8) 0x283e 32 hard yes yes yes
> - * 82801I (ICH9) 0x2930 32 hard yes yes yes
> - * EP80579 (Tolapai) 0x5032 32 hard yes yes yes
> - * ICH10 0x3a30 32 hard yes yes yes
> - * ICH10 0x3a60 32 hard yes yes yes
> - * 5/3400 Series (PCH) 0x3b30 32 hard yes yes yes
> - * 6 Series (PCH) 0x1c22 32 hard yes yes yes
> - * Patsburg (PCH) 0x1d22 32 hard yes yes yes
> - * Patsburg (PCH) IDF 0x1d70 32 hard yes yes yes
> - * Patsburg (PCH) IDF 0x1d71 32 hard yes yes yes
> - * Patsburg (PCH) IDF 0x1d72 32 hard yes yes yes
> - * DH89xxCC (PCH) 0x2330 32 hard yes yes yes
> - * Panther Point (PCH) 0x1e22 32 hard yes yes yes
> - * Lynx Point (PCH) 0x8c22 32 hard yes yes yes
> - * Lynx Point-LP (PCH) 0x9c22 32 hard yes yes yes
> - * Avoton (SOC) 0x1f3c 32 hard yes yes yes
> - * Wellsburg (PCH) 0x8d22 32 hard yes yes yes
> - * Wellsburg (PCH) MS 0x8d7d 32 hard yes yes yes
> - * Wellsburg (PCH) MS 0x8d7e 32 hard yes yes yes
> - * Wellsburg (PCH) MS 0x8d7f 32 hard yes yes yes
> - * Coleto Creek (PCH) 0x23b0 32 hard yes yes yes
> - * Wildcat Point (PCH) 0x8ca2 32 hard yes yes yes
> - * Wildcat Point-LP (PCH) 0x9ca2 32 hard yes yes yes
> - * BayTrail (SOC) 0x0f12 32 hard yes yes yes
> - * Sunrise Point-H (PCH) 0xa123 32 hard yes yes yes
> - * Sunrise Point-LP (PCH) 0x9d23 32 hard yes yes yes
> + * I/O SMBus Block I2C
> + * region Host SMBus Block proc. block
> + * Chip name PCI ID size notify PEC buffer call read
> + * ----------------------------------------------------------------------------------
> + * 82801AA (ICH) 0x2413 16 no no no no no
> + * 82801AB (ICH0) 0x2423 16 no no no no no
> + * 82801BA (ICH2) 0x2443 16 no no no no no
> + * 82801CA (ICH3) 0x2483 32 yes soft no no no
> + * 82801DB (ICH4) 0x24c3 32 yes hard yes no no
> + * 82801E (ICH5) 0x24d3 32 yes hard yes yes yes
> + * 6300ESB 0x25a4 32 yes hard yes yes yes
> + * 82801F (ICH6) 0x266a 32 yes hard yes yes yes
> + * 6310ESB/6320ESB 0x269b 32 yes hard yes yes yes
> + * 82801G (ICH7) 0x27da 32 yes hard yes yes yes
> + * 82801H (ICH8) 0x283e 32 yes hard yes yes yes
> + * 82801I (ICH9) 0x2930 32 yes hard yes yes yes
> + * EP80579 (Tolapai) 0x5032 32 yes hard yes yes yes
> + * ICH10 0x3a30 32 yes hard yes yes yes
> + * ICH10 0x3a60 32 yes hard yes yes yes
> + * 5/3400 Series (PCH) 0x3b30 32 yes hard yes yes yes
> + * 6 Series (PCH) 0x1c22 32 yes hard yes yes yes
> + * Patsburg (PCH) 0x1d22 32 yes hard yes yes yes
> + * Patsburg (PCH) IDF 0x1d70 32 yes hard yes yes yes
> + * Patsburg (PCH) IDF 0x1d71 32 yes hard yes yes yes
> + * Patsburg (PCH) IDF 0x1d72 32 yes hard yes yes yes
> + * DH89xxCC (PCH) 0x2330 32 yes hard yes yes yes
> + * Panther Point (PCH) 0x1e22 32 yes hard yes yes yes
> + * Lynx Point (PCH) 0x8c22 32 yes hard yes yes yes
> + * Lynx Point-LP (PCH) 0x9c22 32 yes hard yes yes yes
> + * Avoton (SOC) 0x1f3c 32 yes hard yes yes yes
> + * Wellsburg (PCH) 0x8d22 32 yes hard yes yes yes
> + * Wellsburg (PCH) MS 0x8d7d 32 yes hard yes yes yes
> + * Wellsburg (PCH) MS 0x8d7e 32 yes hard yes yes yes
> + * Wellsburg (PCH) MS 0x8d7f 32 yes hard yes yes yes
> + * Coleto Creek (PCH) 0x23b0 32 yes hard yes yes yes
> + * Wildcat Point (PCH) 0x8ca2 32 yes hard yes yes yes
> + * Wildcat Point-LP (PCH) 0x9ca2 32 yes hard yes yes yes
> + * BayTrail (SOC) 0x0f12 32 yes hard yes yes yes
> + * Sunrise Point-H (PCH) 0xa123 32 yes hard yes yes yes
> + * Sunrise Point-LP (PCH) 0x9d23 32 yes hard yes yes yes
> *
> * Features supported by this driver:
> * Software PEC no
> @@ -68,6 +68,7 @@
> * Block process call transaction no
> * I2C block read transaction yes (doesn't use the block buffer)
> * Slave mode no
> + * SMBus Host Notify yes
> * Interrupt processing yes
> *
> * See the file Documentation/i2c/busses/i2c-i801 for details.
> @@ -82,6 +83,7 @@
> #include <linux/ioport.h>
> #include <linux/init.h>
> #include <linux/i2c.h>
> +#include <linux/i2c-smbus.h>
> #include <linux/acpi.h>
> #include <linux/io.h>
> #include <linux/dmi.h>
> @@ -107,6 +109,10 @@
> #define SMBPEC(p) (8 + (p)->smba) /* ICH3 and later */
> #define SMBAUXSTS(p) (12 + (p)->smba) /* ICH4 and later */
> #define SMBAUXCTL(p) (13 + (p)->smba) /* ICH4 and later */
> +#define SMBSLVSTS(p) (16 + (p)->smba) /* ICH3 and later */
> +#define SMBSLVCMD(p) (17 + (p)->smba) /* ICH3 and later */
> +#define SMBNTFDADD(p) (20 + (p)->smba) /* ICH3 and later */
> +#define SMBNTFDDAT(p) (22 + (p)->smba) /* ICH3 and later */
>
> /* PCI Address Constants */
> #define SMBBAR 4
> @@ -158,6 +164,12 @@
> #define SMBHSTSTS_INTR 0x02
> #define SMBHSTSTS_HOST_BUSY 0x01
>
> +/* Host Notify Status registers bits */
> +#define SMBSLVSTS_HST_NTFY_STS 1
> +
> +/* Host Notify Command registers bits */
> +#define SMBSLVCMD_HST_NTFY_INTREN 0x01
> +
> #define STATUS_ERROR_FLAGS (SMBHSTSTS_FAILED | SMBHSTSTS_BUS_ERR | \
> SMBHSTSTS_DEV_ERR)
>
> @@ -221,13 +233,18 @@ struct i801_priv {
> const struct i801_mux_config *mux_drvdata;
> struct platform_device *mux_pdev;
> #endif
> +
> + struct work_struct host_notify;
> };
>
> +#define SMBHSTNTFY_SIZE 8
> +
> #define FEATURE_SMBUS_PEC (1 << 0)
> #define FEATURE_BLOCK_BUFFER (1 << 1)
> #define FEATURE_BLOCK_PROC (1 << 2)
> #define FEATURE_I2C_BLOCK_READ (1 << 3)
> #define FEATURE_IRQ (1 << 4)
> +#define FEATURE_HOST_NOTIFY (1 << 5)
> /* Not really a feature, but it's convenient to handle it as such */
> #define FEATURE_IDF (1 << 15)
>
> @@ -237,6 +254,7 @@ static const char *i801_feature_names[] = {
> "Block process call",
> "I2C block read",
> "Interrupt",
> + "SMBus Host Notify",
> };
>
> static unsigned int disable_features;
> @@ -245,7 +263,8 @@ MODULE_PARM_DESC(disable_features, "Disable selected driver features:\n"
> "\t\t 0x01 disable SMBus PEC\n"
> "\t\t 0x02 disable the block buffer\n"
> "\t\t 0x08 disable the I2C block read functionality\n"
> - "\t\t 0x10 don't use interrupts ");
> + "\t\t 0x10 don't use interrupts\n"
> + "\t\t 0x20 disable SMBus Host Notify ");
>
> /* Make sure the SMBus host is ready to start transmitting.
> Return 0 if it is, -EBUSY if it is not. */
> @@ -480,7 +499,36 @@ static void i801_isr_byte_done(struct i801_priv *priv)
> }
>
> /*
> - * There are two kinds of interrupts:
> + * The Host Notify IRQ handler needs to hand work off to a task which can
> + * sleep, because i2c_propagate_smbus_host_notify() can't be called in IRQ
> + * context.
> + */
> +static void i801_host_notify(struct work_struct *work)
> +{
> + struct i801_priv *priv;
> + unsigned short addr;
> + unsigned int data;
> +
> + priv = container_of(work, struct i801_priv, host_notify);
> +
> + addr = inb_p(SMBNTFDADD(priv)) >> 1;
> + data = inw_p(SMBNTFDDAT(priv));
> +
> + /* clear Host Notify bit to allow a new interrupt */
> + outb_p(SMBSLVSTS_HST_NTFY_STS, SMBSLVSTS(priv));
> +
> + i2c_propagate_smbus_host_notify(&priv->adapter, addr, data);
Unfortunately, it looks like this is prone to races.
We encountered a bug which makes the controller to time out when reading
data with this implementation. If there are too many I2C transactions in
the IRQ (i.e. something like 2, which can be considered as a big number :-P )
then the controller is messed up. I am working on a fix in i2c-smbus
which allows to call i2c_propagate_smbus_host_notify() from an
uninterruptible context (like i2c_handle_smbus_alert()). This way, the
registers access are done directly in the IRQ thread and the I2C
transactions will be done afterwards.
So please disregard this series, I will send a v4 hopefully soonish.
Cheers,
Benjamin
> +}
> +
> +static irqreturn_t i801_host_notify_isr(struct i801_priv *priv)
> +{
> + schedule_work(&priv->host_notify);
> +
> + return IRQ_HANDLED;
> +}
> +
> +/*
> + * There are three kinds of interrupts:
> *
> * 1) i801 signals transaction completion with one of these interrupts:
> * INTR - Success
> @@ -492,6 +540,8 @@ static void i801_isr_byte_done(struct i801_priv *priv)
> *
> * 2) For byte-by-byte (I2C read/write) transactions, one BYTE_DONE interrupt
> * occurs for each byte of a byte-by-byte to prepare the next byte.
> + *
> + * 3) Host Notify interrupts
> */
> static irqreturn_t i801_isr(int irq, void *dev_id)
> {
> @@ -504,6 +554,12 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
> if (!(pcists & SMBPCISTS_INTS))
> return IRQ_NONE;
>
> + if (priv->features & FEATURE_HOST_NOTIFY) {
> + status = inb_p(SMBSLVSTS(priv));
> + if (status & SMBSLVSTS_HST_NTFY_STS)
> + return i801_host_notify_isr(priv);
> + }
> +
> status = inb_p(SMBHSTSTS(priv));
> if (status & SMBHSTSTS_BYTE_DONE)
> i801_isr_byte_done(priv);
> @@ -801,7 +857,21 @@ static u32 i801_func(struct i2c_adapter *adapter)
> I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_WRITE_I2C_BLOCK |
> ((priv->features & FEATURE_SMBUS_PEC) ? I2C_FUNC_SMBUS_PEC : 0) |
> ((priv->features & FEATURE_I2C_BLOCK_READ) ?
> - I2C_FUNC_SMBUS_READ_I2C_BLOCK : 0);
> + I2C_FUNC_SMBUS_READ_I2C_BLOCK : 0) |
> + ((priv->features & FEATURE_HOST_NOTIFY) ?
> + I2C_FUNC_SMBUS_HOST_NOTIFY : 0);
> +}
> +
> +static void i801_enable_host_notify(struct i2c_adapter *adapter)
> +{
> + struct i801_priv *priv = i2c_get_adapdata(adapter);
> +
> + if (!(priv->features & FEATURE_HOST_NOTIFY))
> + return;
> +
> + outb_p(SMBSLVCMD_HST_NTFY_INTREN, SMBSLVCMD(priv));
> + /* clear Host Notify bit to allow a new notification */
> + outb_p(SMBSLVSTS_HST_NTFY_STS, SMBSLVSTS(priv));
> }
>
> static const struct i2c_algorithm smbus_algorithm = {
> @@ -1166,6 +1236,8 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
> priv->features |= FEATURE_BLOCK_BUFFER;
> /* fall through */
> case PCI_DEVICE_ID_INTEL_82801CA_3:
> + priv->features |= FEATURE_HOST_NOTIFY;
> + /* fall through */
> case PCI_DEVICE_ID_INTEL_82801BA_2:
> case PCI_DEVICE_ID_INTEL_82801AB_3:
> case PCI_DEVICE_ID_INTEL_82801AA_3:
> @@ -1250,6 +1322,8 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
> }
> }
>
> + INIT_WORK(&priv->host_notify, i801_host_notify);
> +
> if (priv->features & FEATURE_IRQ) {
> init_waitqueue_head(&priv->waitq);
>
> @@ -1279,6 +1353,13 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
> return err;
> }
>
> + /*
> + * Enable Host Notify for chips that supports it.
> + * It is done after i2c_add_adapter() so that we are sure the work queue
> + * is not used if i2c_add_adapter() fails.
> + */
> + i801_enable_host_notify(&priv->adapter);
> +
> i801_probe_optional_slaves(priv);
> /* We ignore errors - multiplexing is optional */
> i801_add_mux(priv);
> @@ -1292,6 +1373,8 @@ static void i801_remove(struct pci_dev *dev)
> {
> struct i801_priv *priv = pci_get_drvdata(dev);
>
> + cancel_work_sync(&priv->host_notify);
> +
> i801_del_mux(priv);
> i2c_del_adapter(&priv->adapter);
> pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);
> @@ -1315,8 +1398,11 @@ static int i801_suspend(struct pci_dev *dev, pm_message_t mesg)
>
> static int i801_resume(struct pci_dev *dev)
> {
> + struct i801_priv *priv = pci_get_drvdata(dev);
> +
> pci_set_power_state(dev, PCI_D0);
> pci_restore_state(dev);
> + i801_enable_host_notify(&priv->adapter);
> return 0;
> }
> #else
> --
> 2.4.3
>
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