[PATCH v2 2/2] timer: Return count from timer_ops.get_count

Sean Anderson seanga2 at gmail.com
Wed Oct 7 20:37:44 CEST 2020 

No timer drivers return an error from get_count. Instead of possibly
returning an error, just return the count directly.

Signed-off-by: Sean Anderson <seanga2 at gmail.com>
---

Changes in v2:
- mchp-pit64b was added since v1, so convert it
- Document when get_count may be called, and what assumptions the timer
  subsystem makes about drivers

 arch/riscv/lib/andes_plmt.c       |  6 ++----
 arch/riscv/lib/sifive_clint.c     |  6 ++----
 drivers/timer/ag101p_timer.c      |  5 ++---
 drivers/timer/altera_timer.c      |  6 ++----
 drivers/timer/arc_timer.c         |  6 ++----
 drivers/timer/ast_timer.c         |  6 ++----
 drivers/timer/atcpit100_timer.c   |  5 ++---
 drivers/timer/atmel_pit_timer.c   |  6 ++----
 drivers/timer/cadence-ttc.c       |  6 ++----
 drivers/timer/dw-apb-timer.c      |  6 ++----
 drivers/timer/mchp-pit64b-timer.c |  6 ++----
 drivers/timer/mpc83xx_timer.c     |  6 ++----
 drivers/timer/mtk_timer.c         |  6 ++----
 drivers/timer/nomadik-mtu-timer.c |  6 ++----
 drivers/timer/omap-timer.c        |  6 ++----
 drivers/timer/ostm_timer.c        |  6 ++----
 drivers/timer/riscv_timer.c       | 21 +++++++++------------
 drivers/timer/rockchip_timer.c    |  5 ++---
 drivers/timer/sandbox_timer.c     |  6 ++----
 drivers/timer/sti-timer.c         |  6 ++----
 drivers/timer/stm32_timer.c       |  6 ++----
 drivers/timer/timer-uclass.c      |  3 ++-
 drivers/timer/tsc_timer.c         |  6 ++----
 include/timer.h                   |  9 ++++++---
 24 files changed, 59 insertions(+), 97 deletions(-)

diff --git a/arch/riscv/lib/andes_plmt.c b/arch/riscv/lib/andes_plmt.c
index a28c14c1eb..cec86718c7 100644
--- a/arch/riscv/lib/andes_plmt.c
+++ b/arch/riscv/lib/andes_plmt.c
@@ -17,11 +17,9 @@
 /* mtime register */
 #define MTIME_REG(base)			((ulong)(base))
 
-static int andes_plmt_get_count(struct udevice *dev, u64 *count)
+static u64 andes_plmt_get_count(struct udevice *dev)
 {
-	*count = readq((void __iomem *)MTIME_REG(dev->priv));
-
-	return 0;
+	return readq((void __iomem *)MTIME_REG(dev->priv));
 }
 
 static const struct timer_ops andes_plmt_ops = {
diff --git a/arch/riscv/lib/sifive_clint.c b/arch/riscv/lib/sifive_clint.c
index c9704c596f..a5572cb825 100644
--- a/arch/riscv/lib/sifive_clint.c
+++ b/arch/riscv/lib/sifive_clint.c
@@ -62,11 +62,9 @@ int riscv_get_ipi(int hart, int *pending)
 	return 0;
 }
 
-static int sifive_clint_get_count(struct udevice *dev, u64 *count)
+static u64 sifive_clint_get_count(struct udevice *dev)
 {
-	*count = readq((void __iomem *)MTIME_REG(dev->priv));
-
-	return 0;
+	return readq((void __iomem *)MTIME_REG(dev->priv));
 }
 
 static const struct timer_ops sifive_clint_ops = {
diff --git a/drivers/timer/ag101p_timer.c b/drivers/timer/ag101p_timer.c
index c011906b93..23ad5b2b67 100644
--- a/drivers/timer/ag101p_timer.c
+++ b/drivers/timer/ag101p_timer.c
@@ -62,14 +62,13 @@ struct atftmr_timer_platdata {
 	struct atftmr_timer_regs *regs;
 };
 
-static int atftmr_timer_get_count(struct udevice *dev, u64 *count)
+static u64 atftmr_timer_get_count(struct udevice *dev)
 {
 	struct atftmr_timer_platdata *plat = dev->platdata;
 	struct atftmr_timer_regs *const regs = plat->regs;
 	u32 val;
 	val = readl(&regs->t3_counter);
-	*count = timer_conv_64(val);
-	return 0;
+	return timer_conv_64(val);
 }
 
 static int atftmr_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/altera_timer.c b/drivers/timer/altera_timer.c
index 6cb2923e0b..ccc164ee17 100644
--- a/drivers/timer/altera_timer.c
+++ b/drivers/timer/altera_timer.c
@@ -32,7 +32,7 @@ struct altera_timer_platdata {
 	struct altera_timer_regs *regs;
 };
 
-static int altera_timer_get_count(struct udevice *dev, u64 *count)
+static u64 altera_timer_get_count(struct udevice *dev)
 {
 	struct altera_timer_platdata *plat = dev->platdata;
 	struct altera_timer_regs *const regs = plat->regs;
@@ -44,9 +44,7 @@ static int altera_timer_get_count(struct udevice *dev, u64 *count)
 	/* Read timer value */
 	val = readl(&regs->snapl) & 0xffff;
 	val |= (readl(&regs->snaph) & 0xffff) << 16;
-	*count = timer_conv_64(~val);
-
-	return 0;
+	return timer_conv_64(~val);
 }
 
 static int altera_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/arc_timer.c b/drivers/timer/arc_timer.c
index 8c574ec5af..2dea9f40cb 100644
--- a/drivers/timer/arc_timer.c
+++ b/drivers/timer/arc_timer.c
@@ -26,7 +26,7 @@ struct arc_timer_priv {
 		uint timer_id;
 };
 
-static int arc_timer_get_count(struct udevice *dev, u64 *count)
+static u64 arc_timer_get_count(struct udevice *dev)
 {
 	u32 val = 0;
 	struct arc_timer_priv *priv = dev_get_priv(dev);
@@ -39,9 +39,7 @@ static int arc_timer_get_count(struct udevice *dev, u64 *count)
 		val = read_aux_reg(ARC_AUX_TIMER1_CNT);
 		break;
 	}
-	*count = timer_conv_64(val);
-
-	return 0;
+	return timer_conv_64(val);
 }
 
 static int arc_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/ast_timer.c b/drivers/timer/ast_timer.c
index e313249740..35369a4087 100644
--- a/drivers/timer/ast_timer.c
+++ b/drivers/timer/ast_timer.c
@@ -51,13 +51,11 @@ static int ast_timer_probe(struct udevice *dev)
 	return 0;
 }
 
-static int ast_timer_get_count(struct udevice *dev, u64 *count)
+static u64 ast_timer_get_count(struct udevice *dev)
 {
 	struct ast_timer_priv *priv = dev_get_priv(dev);
 
-	*count = AST_TMC_RELOAD_VAL - readl(&priv->tmc->status);
-
-	return 0;
+	return AST_TMC_RELOAD_VAL - readl(&priv->tmc->status);
 }
 
 static int ast_timer_ofdata_to_platdata(struct udevice *dev)
diff --git a/drivers/timer/atcpit100_timer.c b/drivers/timer/atcpit100_timer.c
index 5d4ae68509..fcb8a45358 100644
--- a/drivers/timer/atcpit100_timer.c
+++ b/drivers/timer/atcpit100_timer.c
@@ -68,13 +68,12 @@ struct atcpit_timer_platdata {
 	u32 *regs;
 };
 
-static int atcpit_timer_get_count(struct udevice *dev, u64 *count)
+static u64 atcpit_timer_get_count(struct udevice *dev)
 {
 	struct atcpit_timer_platdata *plat = dev_get_platdata(dev);
 	u32 val;
 	val = ~(REG32_TMR(CH_CNT(1))+0xffffffff);
-	*count = timer_conv_64(val);
-	return 0;
+	return timer_conv_64(val);
 }
 
 static int atcpit_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/atmel_pit_timer.c b/drivers/timer/atmel_pit_timer.c
index 843d670b5e..9f0ad1d703 100644
--- a/drivers/timer/atmel_pit_timer.c
+++ b/drivers/timer/atmel_pit_timer.c
@@ -25,15 +25,13 @@ struct atmel_pit_platdata {
 	struct atmel_pit_regs *regs;
 };
 
-static int atmel_pit_get_count(struct udevice *dev, u64 *count)
+static u64 atmel_pit_get_count(struct udevice *dev)
 {
 	struct atmel_pit_platdata *plat = dev_get_platdata(dev);
 	struct atmel_pit_regs *const regs = plat->regs;
 	u32 val = readl(&regs->value_image);
 
-	*count = timer_conv_64(val);
-
-	return 0;
+	return timer_conv_64(val);
 }
 
 static int atmel_pit_probe(struct udevice *dev)
diff --git a/drivers/timer/cadence-ttc.c b/drivers/timer/cadence-ttc.c
index e6b6dfe376..bebb2c2e90 100644
--- a/drivers/timer/cadence-ttc.c
+++ b/drivers/timer/cadence-ttc.c
@@ -57,13 +57,11 @@ ulong timer_get_boot_us(void)
 }
 #endif
 
-static int cadence_ttc_get_count(struct udevice *dev, u64 *count)
+static u64 cadence_ttc_get_count(struct udevice *dev)
 {
 	struct cadence_ttc_priv *priv = dev_get_priv(dev);
 
-	*count = readl(&priv->regs->counter_val1);
-
-	return 0;
+	return readl(&priv->regs->counter_val1);
 }
 
 static int cadence_ttc_probe(struct udevice *dev)
diff --git a/drivers/timer/dw-apb-timer.c b/drivers/timer/dw-apb-timer.c
index 35271b20c8..68bc258131 100644
--- a/drivers/timer/dw-apb-timer.c
+++ b/drivers/timer/dw-apb-timer.c
@@ -25,7 +25,7 @@ struct dw_apb_timer_priv {
 	struct reset_ctl_bulk resets;
 };
 
-static int dw_apb_timer_get_count(struct udevice *dev, u64 *count)
+static u64 dw_apb_timer_get_count(struct udevice *dev)
 {
 	struct dw_apb_timer_priv *priv = dev_get_priv(dev);
 
@@ -34,9 +34,7 @@ static int dw_apb_timer_get_count(struct udevice *dev, u64 *count)
 	 * requires the count to be incrementing. Invert the
 	 * result.
 	 */
-	*count = timer_conv_64(~readl(priv->regs + DW_APB_CURR_VAL));
-
-	return 0;
+	return timer_conv_64(~readl(priv->regs + DW_APB_CURR_VAL));
 }
 
 static int dw_apb_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/mchp-pit64b-timer.c b/drivers/timer/mchp-pit64b-timer.c
index ead8c9b84a..ad962098b3 100644
--- a/drivers/timer/mchp-pit64b-timer.c
+++ b/drivers/timer/mchp-pit64b-timer.c
@@ -27,16 +27,14 @@ struct mchp_pit64b_priv {
 	void __iomem *base;
 };
 
-static int mchp_pit64b_get_count(struct udevice *dev, u64 *count)
+static u64 mchp_pit64b_get_count(struct udevice *dev)
 {
 	struct mchp_pit64b_priv *priv = dev_get_priv(dev);
 
 	u32 lsb = readl(priv->base + MCHP_PIT64B_TLSBR);
 	u32 msb = readl(priv->base + MCHP_PIT64B_TMSBR);
 
-	*count = ((u64)msb << 32) | lsb;
-
-	return 0;
+	return ((u64)msb << 32) | lsb;
 }
 
 static int mchp_pit64b_probe(struct udevice *dev)
diff --git a/drivers/timer/mpc83xx_timer.c b/drivers/timer/mpc83xx_timer.c
index ad8bb28e8b..ba7704225a 100644
--- a/drivers/timer/mpc83xx_timer.c
+++ b/drivers/timer/mpc83xx_timer.c
@@ -187,7 +187,7 @@ void wait_ticks(ulong ticks)
 		WATCHDOG_RESET();
 }
 
-static int mpc83xx_timer_get_count(struct udevice *dev, u64 *count)
+static u64 mpc83xx_timer_get_count(struct udevice *dev)
 {
 	u32 tbu, tbl;
 
@@ -201,9 +201,7 @@ static int mpc83xx_timer_get_count(struct udevice *dev, u64 *count)
 		tbl = mftb();
 	} while (tbu != mftbu());
 
-	*count = (tbu * 0x10000ULL) + tbl;
-
-	return 0;
+	return (tbu * 0x10000ULL) + tbl;
 }
 
 static int mpc83xx_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/mtk_timer.c b/drivers/timer/mtk_timer.c
index 69ed521811..74e9ea34ff 100644
--- a/drivers/timer/mtk_timer.c
+++ b/drivers/timer/mtk_timer.c
@@ -27,14 +27,12 @@ struct mtk_timer_priv {
 	void __iomem *base;
 };
 
-static int mtk_timer_get_count(struct udevice *dev, u64 *count)
+static u64 mtk_timer_get_count(struct udevice *dev)
 {
 	struct mtk_timer_priv *priv = dev_get_priv(dev);
 	u32 val = readl(priv->base + MTK_GPT4_CNT);
 
-	*count = timer_conv_64(val);
-
-	return 0;
+	return timer_conv_64(val);
 }
 
 static int mtk_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/nomadik-mtu-timer.c b/drivers/timer/nomadik-mtu-timer.c
index 7ff921385a..d7f7ca4eff 100644
--- a/drivers/timer/nomadik-mtu-timer.c
+++ b/drivers/timer/nomadik-mtu-timer.c
@@ -54,14 +54,12 @@ struct nomadik_mtu_priv {
 	struct nomadik_mtu_timer_regs *timer;
 };
 
-static int nomadik_mtu_get_count(struct udevice *dev, u64 *count)
+static u64 nomadik_mtu_get_count(struct udevice *dev)
 {
 	struct nomadik_mtu_priv *priv = dev_get_priv(dev);
 
 	/* Decrementing counter: invert the value */
-	*count = timer_conv_64(~readl(&priv->timer->cv));
-
-	return 0;
+	return timer_conv_64(~readl(&priv->timer->cv));
 }
 
 static int nomadik_mtu_probe(struct udevice *dev)
diff --git a/drivers/timer/omap-timer.c b/drivers/timer/omap-timer.c
index cf3d27b96b..4eecb3e64d 100644
--- a/drivers/timer/omap-timer.c
+++ b/drivers/timer/omap-timer.c
@@ -48,13 +48,11 @@ struct omap_timer_priv {
 	struct omap_gptimer_regs *regs;
 };
 
-static int omap_timer_get_count(struct udevice *dev, u64 *count)
+static u64 omap_timer_get_count(struct udevice *dev)
 {
 	struct omap_timer_priv *priv = dev_get_priv(dev);
 
-	*count = timer_conv_64(readl(&priv->regs->tcrr));
-
-	return 0;
+	return timer_conv_64(readl(&priv->regs->tcrr));
 }
 
 static int omap_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/ostm_timer.c b/drivers/timer/ostm_timer.c
index bea97159eb..bb0636a071 100644
--- a/drivers/timer/ostm_timer.c
+++ b/drivers/timer/ostm_timer.c
@@ -27,13 +27,11 @@ struct ostm_priv {
 	fdt_addr_t	regs;
 };
 
-static int ostm_get_count(struct udevice *dev, u64 *count)
+static u64 ostm_get_count(struct udevice *dev)
 {
 	struct ostm_priv *priv = dev_get_priv(dev);
 
-	*count = timer_conv_64(readl(priv->regs + OSTM_CNT));
-
-	return 0;
+	return timer_conv_64(readl(priv->regs + OSTM_CNT));
 }
 
 static int ostm_probe(struct udevice *dev)
diff --git a/drivers/timer/riscv_timer.c b/drivers/timer/riscv_timer.c
index 449fcfcfd5..21ae184057 100644
--- a/drivers/timer/riscv_timer.c
+++ b/drivers/timer/riscv_timer.c
@@ -16,22 +16,19 @@
 #include <timer.h>
 #include <asm/csr.h>
 
-static int riscv_timer_get_count(struct udevice *dev, u64 *count)
+static u64 riscv_timer_get_count(struct udevice *dev)
 {
-	if (IS_ENABLED(CONFIG_64BIT)) {
-		*count = csr_read(CSR_TIME);
-	} else {
-		u32 hi, lo;
+	__maybe_unused u32 hi, lo;
 
-		do {
-			hi = csr_read(CSR_TIMEH);
-			lo = csr_read(CSR_TIME);
-		} while (hi != csr_read(CSR_TIMEH));
+	if (IS_ENABLED(CONFIG_64BIT))
+		return csr_read(CSR_TIME);
 
-		*count = ((u64)hi << 32) | lo;
-	}
+	do {
+		hi = csr_read(CSR_TIMEH);
+		lo = csr_read(CSR_TIME);
+	} while (hi != csr_read(CSR_TIMEH));
 
-	return 0;
+	return ((u64)hi << 32) | lo;
 }
 
 static int riscv_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/rockchip_timer.c b/drivers/timer/rockchip_timer.c
index 7a5a484252..53cdf09810 100644
--- a/drivers/timer/rockchip_timer.c
+++ b/drivers/timer/rockchip_timer.c
@@ -88,14 +88,13 @@ ulong timer_get_boot_us(void)
 }
 #endif
 
-static int rockchip_timer_get_count(struct udevice *dev, u64 *count)
+static u64 rockchip_timer_get_count(struct udevice *dev)
 {
 	struct rockchip_timer_priv *priv = dev_get_priv(dev);
 	uint64_t cntr = rockchip_timer_get_curr_value(priv->timer);
 
 	/* timers are down-counting */
-	*count = ~0ull - cntr;
-	return 0;
+	return ~0ull - cntr;
 }
 
 static int rockchip_clk_ofdata_to_platdata(struct udevice *dev)
diff --git a/drivers/timer/sandbox_timer.c b/drivers/timer/sandbox_timer.c
index 6a503c2f15..135c0f38a4 100644
--- a/drivers/timer/sandbox_timer.c
+++ b/drivers/timer/sandbox_timer.c
@@ -29,11 +29,9 @@ unsigned long notrace timer_early_get_rate(void)
 	return SANDBOX_TIMER_RATE;
 }
 
-static notrace int sandbox_timer_get_count(struct udevice *dev, u64 *count)
+static notrace u64 sandbox_timer_get_count(struct udevice *dev)
 {
-	*count = timer_early_get_count();
-
-	return 0;
+	return timer_early_get_count();
 }
 
 static int sandbox_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/sti-timer.c b/drivers/timer/sti-timer.c
index ff42056abd..e6843ebb33 100644
--- a/drivers/timer/sti-timer.c
+++ b/drivers/timer/sti-timer.c
@@ -17,7 +17,7 @@ struct sti_timer_priv {
 	struct globaltimer *global_timer;
 };
 
-static int sti_timer_get_count(struct udevice *dev, u64 *count)
+static u64 sti_timer_get_count(struct udevice *dev)
 {
 	struct sti_timer_priv *priv = dev_get_priv(dev);
 	struct globaltimer *global_timer = priv->global_timer;
@@ -34,9 +34,7 @@ static int sti_timer_get_count(struct udevice *dev, u64 *count)
 			old = high;
 	}
 	timer = high;
-	*count = (u64)((timer << 32) | low);
-
-	return 0;
+	return (u64)((timer << 32) | low);
 }
 
 static int sti_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/stm32_timer.c b/drivers/timer/stm32_timer.c
index c57fa3f557..f517d5e61f 100644
--- a/drivers/timer/stm32_timer.c
+++ b/drivers/timer/stm32_timer.c
@@ -52,14 +52,12 @@ struct stm32_timer_priv {
 	struct stm32_timer_regs *base;
 };
 
-static int stm32_timer_get_count(struct udevice *dev, u64 *count)
+static u64 stm32_timer_get_count(struct udevice *dev)
 {
 	struct stm32_timer_priv *priv = dev_get_priv(dev);
 	struct stm32_timer_regs *regs = priv->base;
 
-	*count = readl(&regs->cnt);
-
-	return 0;
+	return readl(&regs->cnt);
 }
 
 static int stm32_timer_probe(struct udevice *dev)
diff --git a/drivers/timer/timer-uclass.c b/drivers/timer/timer-uclass.c
index e9802c8b43..53a8dfb316 100644
--- a/drivers/timer/timer-uclass.c
+++ b/drivers/timer/timer-uclass.c
@@ -33,7 +33,8 @@ int notrace timer_get_count(struct udevice *dev, u64 *count)
 	if (!ops->get_count)
 		return -ENOSYS;
 
-	return ops->get_count(dev, count);
+	*count = ops->get_count(dev);
+	return 0;
 }
 
 unsigned long notrace timer_get_rate(struct udevice *dev)
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 93c959ff44..abc0a1da05 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -386,13 +386,11 @@ void __udelay(unsigned long usec)
 #endif
 }
 
-static int tsc_timer_get_count(struct udevice *dev, u64 *count)
+static u64 tsc_timer_get_count(struct udevice *dev)
 {
 	u64 now_tick = rdtsc();
 
-	*count = now_tick - gd->arch.tsc_base;
-
-	return 0;
+	return now_tick - gd->arch.tsc_base;
 }
 
 static void tsc_timer_ensure_setup(bool early)
diff --git a/include/timer.h b/include/timer.h
index aa9d870619..a044cb034e 100644
--- a/include/timer.h
+++ b/include/timer.h
@@ -67,11 +67,14 @@ struct timer_ops {
 	 *
 	 * @dev: The timer device
 	 *
-	 * @count: pointer that returns the current 64-bit timer count
+	 * This function may be called at any time after the driver is probed.
+	 * All necessary initialization must be completed by the time probe()
+	 * returns. The count returned by this functions should be monotonic.
+	 * This function must succeed.
 	 *
-	 * Return: 0 if OK, -ve on error
+	 * Return: The current 64-bit timer count
 	 */
-	int (*get_count)(struct udevice *dev, u64 *count);
+	u64 (*get_count)(struct udevice *dev);
 };
 
 /**
-- 
2.28.0

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