The qpnpint_irq_set_type() callback function configures the type (edge vs level) and polarity (high, low, or both) of a particular PMIC interrupt within a given peripheral. To do this, it reads the three consecutive IRQ configuration registers, modifies the specified IRQ bit within the register values, and finally writes the three modified register values back to the PMIC. While a spinlock is used to provide mutual exclusion on the SPMI bus during the register read and write calls, there is no locking around the overall read, modify, write sequence. This opens up the possibility of a race condition if two tasks set the type of a PMIC IRQ within the same peripheral simultaneously. When the race condition is encountered, both tasks will read the old value of the registers and IRQ bits set by one of the tasks will be dropped upon the register write of the other task. This then leads to PMIC IRQs being enabled with an incorrect type and polarity configured. Such misconfiguration can lead to an IRQ storm that overwhelms the system and causes it to crash. This race condition and IRQ storm have been observed when using a pair of pm8941-pwrkey devices to handle PMK8350 pwrkey and resin interrupts. The independent devices probe asynchronously in parallel and can simultaneously request and configure PMIC IRQs in the same PMIC peripheral. For a good case, the IRQ configuration calls end up serialized due to timing deltas and the register read/write sequence looks like this: 1. pwrkey probe: SPMI read(0x1311): 0x00, 0x00, 0x00 2. pwrkey probe: SPMI write(0x1311): 0x80, 0x80, 0x80 3. resin probe: SPMI read(0x1311): 0x80, 0x80, 0x80 4. resin probe: SPMI write(0x1311): 0xC0, 0xC0, 0xC0 The final register states after both devices have requested and enabled their respective IRQs is thus: 0x1311: 0xC0 0x1312: 0xC0 0x1313: 0xC0 0x1314: 0x00 0x1315: 0xC0 For a bad case, the IRQ configuration calls end up occurring simultaneously and the race condition is encountered. The register read/write sequence then looks like this: 1. pwrkey probe: SPMI read(0x1311): 0x00, 0x00, 0x00 2. resin probe: SPMI read(0x1311): 0x00, 0x00, 0x00 3. pwrkey probe: SPMI write(0x1311): 0x80, 0x80, 0x80 4. resin probe: SPMI write(0x1311): 0x40, 0x40, 0x40 In this case, the final register states after both devices have requested and enabled their respective IRQs is thus: 0x1311: 0x40 0x1312: 0x40 0x1313: 0x40 0x1314: 0x00 0x1315: 0xC0 This corresponds to the resin IRQ being configured for both rising and falling edges, as expected. However, the pwrkey IRQ is misconfigured as level type with both polarity high and low set to disabled. The PMIC IRQ triggering hardware treats this particular register configuration as if level low triggering is enabled. The raw pwrkey IRQ signal is low when the power key is not being pressed. Thus, the pwrkey IRQ begins firing continuously in an IRQ storm. Fix the race condition by holding the spmi-pmic-arb spinlock for the duration of the read, modify, write sequence performed in the qpnpint_irq_set_type() function. Split the pmic_arb_read_cmd() and pmic_arb_write_cmd() functions each into three parts so that hardware register IO is decoupled from spinlock locking. This allows a new function pmic_arb_masked_write() to be added which locks the spinlock and then calls register IO functions to perform SPMI read and write commands in a single atomic operation. Signed-off-by: David Collins <quic_collinsd@xxxxxxxxxxx> --- Changes in v2: - Reused existing struct spmi_pmic_arb spinlock 'lock' instead of adding a new one for use in qpnpint_irq_set_type() - Split functionality from pmic_arb_read_cmd() into pmic_arb_fmt_read_cmd() and pmic_arb_read_cmd_unlocked() - Split functionality from pmic_arb_write_cmd() into pmic_arb_fmt_write_cmd() and pmic_arb_write_cmd_unlocked() - Added pmic_arb_masked_write() function which calls pmic_arb_fmt_read_cmd() and pmic_arb_fmt_write_cmd() then locks the spinlock and calls pmic_arb_read_cmd_unlocked() and pmic_arb_write_cmd_unlocked() - Added qpnpint_spmi_masked_write() as a light wrapper around pmic_arb_masked_write() - Modified qpnpint_irq_set_type() to make use of qpnpint_spmi_masked_write(). v1 of this patch can be found at [1]. [1]: https://lore.kernel.org/all/20210728180209.14764-1-collinsd@xxxxxxxxxxxxxx --- drivers/spmi/spmi-pmic-arb.c | 176 ++++++++++++++++++++++++++++------- 1 file changed, 140 insertions(+), 36 deletions(-) diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c index bbbd311eda03..6e0f450ed20f 100644 --- a/drivers/spmi/spmi-pmic-arb.c +++ b/drivers/spmi/spmi-pmic-arb.c @@ -333,24 +333,20 @@ static int pmic_arb_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid) return pmic_arb->ver_ops->non_data_cmd(ctrl, opc, sid); } -static int pmic_arb_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, - u16 addr, u8 *buf, size_t len) +static int pmic_arb_fmt_read_cmd(struct spmi_pmic_arb *pmic_arb, u8 opc, u8 sid, + u16 addr, size_t len, u32 *cmd, u32 *offset) { - struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); - unsigned long flags; u8 bc = len - 1; - u32 cmd; int rc; - u32 offset; rc = pmic_arb->ver_ops->offset(pmic_arb, sid, addr, PMIC_ARB_CHANNEL_OBS); if (rc < 0) return rc; - offset = rc; + *offset = rc; if (bc >= PMIC_ARB_MAX_TRANS_BYTES) { - dev_err(&ctrl->dev, "pmic-arb supports 1..%d bytes per trans, but:%zu requested", + dev_err(&pmic_arb->spmic->dev, "pmic-arb supports 1..%d bytes per trans, but:%zu requested", PMIC_ARB_MAX_TRANS_BYTES, len); return -EINVAL; } @@ -365,14 +361,24 @@ static int pmic_arb_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, else return -EINVAL; - cmd = pmic_arb->ver_ops->fmt_cmd(opc, sid, addr, bc); + *cmd = pmic_arb->ver_ops->fmt_cmd(opc, sid, addr, bc); + + return 0; +} + +static int pmic_arb_read_cmd_unlocked(struct spmi_controller *ctrl, u32 cmd, + u32 offset, u8 sid, u16 addr, u8 *buf, + size_t len) +{ + struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); + u8 bc = len - 1; + int rc; - raw_spin_lock_irqsave(&pmic_arb->lock, flags); pmic_arb_set_rd_cmd(pmic_arb, offset + PMIC_ARB_CMD, cmd); rc = pmic_arb_wait_for_done(ctrl, pmic_arb->rd_base, sid, addr, PMIC_ARB_CHANNEL_OBS); if (rc) - goto done; + return rc; pmic_arb_read_data(pmic_arb, buf, offset + PMIC_ARB_RDATA0, min_t(u8, bc, 3)); @@ -380,30 +386,44 @@ static int pmic_arb_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, if (bc > 3) pmic_arb_read_data(pmic_arb, buf + 4, offset + PMIC_ARB_RDATA1, bc - 4); + return 0; +} -done: +static int pmic_arb_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, + u16 addr, u8 *buf, size_t len) +{ + struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); + unsigned long flags; + u32 cmd, offset; + int rc; + + rc = pmic_arb_fmt_read_cmd(pmic_arb, opc, sid, addr, len, &cmd, + &offset); + if (rc) + return rc; + + raw_spin_lock_irqsave(&pmic_arb->lock, flags); + rc = pmic_arb_read_cmd_unlocked(ctrl, cmd, offset, sid, addr, buf, len); raw_spin_unlock_irqrestore(&pmic_arb->lock, flags); + return rc; } -static int pmic_arb_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, - u16 addr, const u8 *buf, size_t len) +static int pmic_arb_fmt_write_cmd(struct spmi_pmic_arb *pmic_arb, u8 opc, + u8 sid, u16 addr, size_t len, u32 *cmd, + u32 *offset) { - struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); - unsigned long flags; u8 bc = len - 1; - u32 cmd; int rc; - u32 offset; rc = pmic_arb->ver_ops->offset(pmic_arb, sid, addr, PMIC_ARB_CHANNEL_RW); if (rc < 0) return rc; - offset = rc; + *offset = rc; if (bc >= PMIC_ARB_MAX_TRANS_BYTES) { - dev_err(&ctrl->dev, "pmic-arb supports 1..%d bytes per trans, but:%zu requested", + dev_err(&pmic_arb->spmic->dev, "pmic-arb supports 1..%d bytes per trans, but:%zu requested", PMIC_ARB_MAX_TRANS_BYTES, len); return -EINVAL; } @@ -420,10 +440,19 @@ static int pmic_arb_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, else return -EINVAL; - cmd = pmic_arb->ver_ops->fmt_cmd(opc, sid, addr, bc); + *cmd = pmic_arb->ver_ops->fmt_cmd(opc, sid, addr, bc); + + return 0; +} + +static int pmic_arb_write_cmd_unlocked(struct spmi_controller *ctrl, u32 cmd, + u32 offset, u8 sid, u16 addr, + const u8 *buf, size_t len) +{ + struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); + u8 bc = len - 1; /* Write data to FIFOs */ - raw_spin_lock_irqsave(&pmic_arb->lock, flags); pmic_arb_write_data(pmic_arb, buf, offset + PMIC_ARB_WDATA0, min_t(u8, bc, 3)); if (bc > 3) @@ -432,8 +461,62 @@ static int pmic_arb_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, /* Start the transaction */ pmic_arb_base_write(pmic_arb, offset + PMIC_ARB_CMD, cmd); - rc = pmic_arb_wait_for_done(ctrl, pmic_arb->wr_base, sid, addr, - PMIC_ARB_CHANNEL_RW); + return pmic_arb_wait_for_done(ctrl, pmic_arb->wr_base, sid, addr, + PMIC_ARB_CHANNEL_RW); +} + +static int pmic_arb_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid, + u16 addr, const u8 *buf, size_t len) +{ + struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); + unsigned long flags; + u32 cmd, offset; + int rc; + + rc = pmic_arb_fmt_write_cmd(pmic_arb, opc, sid, addr, len, &cmd, + &offset); + if (rc) + return rc; + + raw_spin_lock_irqsave(&pmic_arb->lock, flags); + rc = pmic_arb_write_cmd_unlocked(ctrl, cmd, offset, sid, addr, buf, + len); + raw_spin_unlock_irqrestore(&pmic_arb->lock, flags); + + return rc; +} + +static int pmic_arb_masked_write(struct spmi_controller *ctrl, u8 sid, u16 addr, + const u8 *buf, const u8 *mask, size_t len) +{ + struct spmi_pmic_arb *pmic_arb = spmi_controller_get_drvdata(ctrl); + u32 read_cmd, read_offset, write_cmd, write_offset; + u8 temp[PMIC_ARB_MAX_TRANS_BYTES]; + unsigned long flags; + int rc, i; + + rc = pmic_arb_fmt_read_cmd(pmic_arb, SPMI_CMD_EXT_READL, sid, addr, len, + &read_cmd, &read_offset); + if (rc) + return rc; + + rc = pmic_arb_fmt_write_cmd(pmic_arb, SPMI_CMD_EXT_WRITEL, sid, addr, + len, &write_cmd, &write_offset); + if (rc) + return rc; + + raw_spin_lock_irqsave(&pmic_arb->lock, flags); + rc = pmic_arb_read_cmd_unlocked(ctrl, read_cmd, read_offset, sid, addr, + temp, len); + if (rc) + goto done; + + for (i = 0; i < len; i++) + temp[i] = (temp[i] & ~mask[i]) | (buf[i] & mask[i]); + + rc = pmic_arb_write_cmd_unlocked(ctrl, write_cmd, write_offset, sid, + addr, temp, len); +done: raw_spin_unlock_irqrestore(&pmic_arb->lock, flags); return rc; @@ -482,6 +565,23 @@ static void qpnpint_spmi_read(struct irq_data *d, u8 reg, void *buf, size_t len) d->irq); } +static int qpnpint_spmi_masked_write(struct irq_data *d, u8 reg, + const void *buf, const void *mask, + size_t len) +{ + struct spmi_pmic_arb *pmic_arb = irq_data_get_irq_chip_data(d); + u8 sid = hwirq_to_sid(d->hwirq); + u8 per = hwirq_to_per(d->hwirq); + int rc; + + rc = pmic_arb_masked_write(pmic_arb->spmic, sid, (per << 8) + reg, buf, + mask, len); + if (rc) + dev_err_ratelimited(&pmic_arb->spmic->dev, "failed irqchip transaction on %x rc=%d\n", + d->irq, rc); + return rc; +} + static void cleanup_irq(struct spmi_pmic_arb *pmic_arb, u16 apid, int id) { u16 ppid = pmic_arb->apid_data[apid].ppid; @@ -600,18 +700,18 @@ static void qpnpint_irq_unmask(struct irq_data *d) static int qpnpint_irq_set_type(struct irq_data *d, unsigned int flow_type) { - struct spmi_pmic_arb_qpnpint_type type; + struct spmi_pmic_arb_qpnpint_type type = {0}; + struct spmi_pmic_arb_qpnpint_type mask; irq_flow_handler_t flow_handler; - u8 irq = hwirq_to_irq(d->hwirq); - - qpnpint_spmi_read(d, QPNPINT_REG_SET_TYPE, &type, sizeof(type)); + u8 irq_bit = BIT(hwirq_to_irq(d->hwirq)); + int rc; if (flow_type & (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)) { - type.type |= BIT(irq); + type.type = irq_bit; if (flow_type & IRQF_TRIGGER_RISING) - type.polarity_high |= BIT(irq); + type.polarity_high = irq_bit; if (flow_type & IRQF_TRIGGER_FALLING) - type.polarity_low |= BIT(irq); + type.polarity_low = irq_bit; flow_handler = handle_edge_irq; } else { @@ -619,19 +719,23 @@ static int qpnpint_irq_set_type(struct irq_data *d, unsigned int flow_type) (flow_type & (IRQF_TRIGGER_LOW))) return -EINVAL; - type.type &= ~BIT(irq); /* level trig */ if (flow_type & IRQF_TRIGGER_HIGH) - type.polarity_high |= BIT(irq); + type.polarity_high = irq_bit; else - type.polarity_low |= BIT(irq); + type.polarity_low = irq_bit; flow_handler = handle_level_irq; } - qpnpint_spmi_write(d, QPNPINT_REG_SET_TYPE, &type, sizeof(type)); + mask.type = irq_bit; + mask.polarity_high = irq_bit; + mask.polarity_low = irq_bit; + + rc = qpnpint_spmi_masked_write(d, QPNPINT_REG_SET_TYPE, &type, &mask, + sizeof(type)); irq_set_handler_locked(d, flow_handler); - return 0; + return rc; } static int qpnpint_irq_set_wake(struct irq_data *d, unsigned int on) -- 2.17.1
