[PATCH 4.19 302/321] mailbox: stm32_ipcc: add spinlock to fix channels concurrent access

Greg Kroah-Hartman
2019-12-03T22:59:16Z

From: Arnaud Pouliquen <arnaud.pouliquen@st.com>

commit dba9a3dfe912dc47c9dbc9ba1f5f65adbf9aea0f upstream.

Add spinlock protection on IPCC register update to avoid race condition.
Without this fix, stm32_ipcc_set_bits and stm32_ipcc_clr_bits can be
called in parallel for different channels. This results in register
corruptions.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mailbox/stm32-ipcc.c | 37 +++++++++++++++++++++++++++----------
1 file changed, 27 insertions(+), 10 deletions(-)

--- a/drivers/mailbox/stm32-ipcc.c
+++ b/drivers/mailbox/stm32-ipcc.c
@@ -50,6 +50,7 @@ struct stm32_ipcc {
void __iomem *reg_base;
void __iomem *reg_proc;
struct clk *clk;
+ spinlock_t lock; /* protect access to IPCC registers */
int irqs[IPCC_IRQ_NUM];
int wkp;
u32 proc_id;
@@ -58,14 +59,24 @@ struct stm32_ipcc {
u32 xmr;
};

-static inline void stm32_ipcc_set_bits(void __iomem *reg, u32 mask)
+static inline void stm32_ipcc_set_bits(spinlock_t *lock, void __iomem *reg,
+ u32 mask)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(lock, flags);
writel_relaxed(readl_relaxed(reg) | mask, reg);
+ spin_unlock_irqrestore(lock, flags);
}

-static inline void stm32_ipcc_clr_bits(void __iomem *reg, u32 mask)
+static inline void stm32_ipcc_clr_bits(spinlock_t *lock, void __iomem *reg,
+ u32 mask)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(lock, flags);
writel_relaxed(readl_relaxed(reg) & ~mask, reg);
+ spin_unlock_irqrestore(lock, flags);
}

static irqreturn_t stm32_ipcc_rx_irq(int irq, void *data)
@@ -92,7 +103,7 @@ static irqreturn_t stm32_ipcc_rx_irq(int

mbox_chan_received_data(&ipcc->controller.chans[chan], NULL);

- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XSCR,
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XSCR,
RX_BIT_CHAN(chan));

ret = IRQ_HANDLED;
@@ -121,7 +132,7 @@ static irqreturn_t stm32_ipcc_tx_irq(int
dev_dbg(dev, "%s: chan:%d tx\n", __func__, chan);

/* mask 'tx channel free' interrupt */
- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XMR,
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XMR,
TX_BIT_CHAN(chan));

mbox_chan_txdone(&ipcc->controller.chans[chan], 0);
@@ -141,10 +152,12 @@ static int stm32_ipcc_send_data(struct m
dev_dbg(ipcc->controller.dev, "%s: chan:%d\n", __func__, chan);

/* set channel n occupied */
- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XSCR, TX_BIT_CHAN(chan));
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XSCR,
+ TX_BIT_CHAN(chan));

/* unmask 'tx channel free' interrupt */
- stm32_ipcc_clr_bits(ipcc->reg_proc + IPCC_XMR, TX_BIT_CHAN(chan));
+ stm32_ipcc_clr_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XMR,
+ TX_BIT_CHAN(chan));

return 0;
}
@@ -163,7 +176,8 @@ static int stm32_ipcc_startup(struct mbo
}

/* unmask 'rx channel occupied' interrupt */
- stm32_ipcc_clr_bits(ipcc->reg_proc + IPCC_XMR, RX_BIT_CHAN(chan));
+ stm32_ipcc_clr_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XMR,
+ RX_BIT_CHAN(chan));

return 0;
}
@@ -175,7 +189,7 @@ static void stm32_ipcc_shutdown(struct m
controller);

/* mask rx/tx interrupt */
- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XMR,
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XMR,
RX_BIT_CHAN(chan) | TX_BIT_CHAN(chan));

clk_disable_unprepare(ipcc->clk);
@@ -208,6 +222,8 @@ static int stm32_ipcc_probe(struct platf
if (!ipcc)
return -ENOMEM;

+ spin_lock_init(&ipcc->lock);
+
/* proc_id */
if (of_property_read_u32(np, "st,proc-id", &ipcc->proc_id)) {
dev_err(dev, "Missing st,proc-id\n");
@@ -259,9 +275,10 @@ static int stm32_ipcc_probe(struct platf
}

/* mask and enable rx/tx irq */
- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XMR,
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XMR,
RX_BIT_MASK | TX_BIT_MASK);
- stm32_ipcc_set_bits(ipcc->reg_proc + IPCC_XCR, XCR_RXOIE | XCR_TXOIE);
+ stm32_ipcc_set_bits(&ipcc->lock, ipcc->reg_proc + IPCC_XCR,
+ XCR_RXOIE | XCR_TXOIE);

/* wakeup */
if (of_property_read_bool(np, "wakeup-source")) {